Okay, so here is my problem...I have a 97 gtp and recently the car has started to give me some trouble. The car starts easily and wonderfully first thing in the morning...once the car has warmed up and/or it is a warm day (like today) any time I start it after the initial starting of the day the car runs rough, bogging down chugging, starving for either fuel or air or something and it either evetually stalls or levels itself out and runs normally. Car has always had a rough idle. This only happens after car has warmed up! NOW...here is what I have done to try and fix this problem. First there are NO codes coming up. I have done plugs, wires, coils, MAF and AIT sensors, changed supercharger oil, changed belts, changed o2 sensors, changed cadalytic convertor, changed air filter cleaned throttle body, unplugged and replugged sensors...this doesn't seem to wanna go away. I have been to 5 mechanics and now I am poor and live up north where premium fuel is 435/gallon. I have serviced fuel system too. ANy help would be much appreciated because I am running out of ideas and credit cards are running out too...HELP please.

sorry to hear that, i have no idea what it could be i would be guessing an ignition problem but idk

chech your fuel pump

thanks, I don't know either and I am so down now..just today I changed all 3 coils and thought that was going to fix it cause I had no codes...so over $100 later and changed them myself (and I am a girl) still have the problem. I was so bummed out...

fuel pump....but only when it is hot? If I go out there right now and fire her up....she will run fine cause I have been home for hours and she has cooled down

Since it acts up after the engine has warmed up, I would try replacing the Engine Coolant Temp Sensor and see if the problem clears up. It's located in the lower intake manifold, below the thermostat. Good time to replace the thermostat as well.

but why no codes?

if it stays within the specs fromt he factory

our cars are mysterious when it comes to throwing codes, sometimes they will, somtimes they wont. but do what blackarrow said, i never thought about that until now.

The Engine Coolant Temp Sensor can go bad, without setting a code. Usually the car runs rich, fuel mileage will suffer, or it won't pass emissions because of higher hydrocarbon (unburnt fuel) levels. The brass part of the sensor becomes coated with anti freeze and the sensor won't lean out the fuel injection when warm. A stuck open thermostat can affect this as well.

what do you guys get for mileage in city?

Here's a recent thread on the subject: Topic: fuel miles per gallon

Blackarrow made a good suggestion, and one that popped into my mind. Otherwise, it's possible a sensor is getting heat-soaked and causing issues. The only real way to find that is to find someone with a scanner or a SnapOn tool that can watch real time data from the sensors and find one that is giving abnormal readings.

Best part about Blackarrow's advice: ECT sensors are only $13 here.

so I changed the ect sensor and the thermo and guess what...still doing it only when hot. I have spent so much money and time and I am really frustrated. The guys at auto part store know me by name and give me a discount now! Any new suggestions? been adding octane boost and seamfoam to gas lately too incase its injectors.

This very well could be a fuel pump problem ,I would suggest getting a Fuel pressure guage this will tell you if your pressure is dropping off at operating temp.Chico(pops)

Just wanted to throw in my two cents, I had this SAME EXACT issue (might not be the same underlying cause) last year, I know you said you changed the MAF sensor, but I would suggest, unplugging the connector from the MAF sensor while the car is running (and is warmed up, giving you the issues you're describing), and see if the engine suddenly stops choking on itself. Your problem is exactly the way mine was -- when the engine was cold everything was golden, after it warmed up and I turned it off and started it again, problems galore with it stalling out!

May not help you since you did change the sensor and all, but it's worth a shot. Yes, it will throw a code too when you unplug it but it's nothing to worry about since you know why it's doing that.

Ended up needing a new MAF, you could be having a MAF sensor issue still, or for that matter, a wiring issue that isn't giving constant readings back to the PCM.

I would like to mention my fuel pump was in the beginning stages of failing at the same time and just about two months ago, it finally died on me -- I really don't think the fuel pump had anything to do with it at the time, but I thought I'd just throw that in as food for thought.

Sorry that didn't work out for you; as Chico suggested, your fuel pump pressure could be falling off when warm (something one of those five mechanics should've checked ). See my comments on fuel pressure here . You can also try the Temp Fuel Pump Resistor Fix (It's free and reversible). Check for fuel in the fuel pressure regulator vacuum hose, and make sure each injector harness is connected to the correct injector/cylinder.
Other possible causes include, but not limited to: Leaking/faulty injectors, faulty ignition module, TPS, MAP sensor, EGR system problem, vacuum leaks, exhaust system blockage or restrictions, problems in any of the related wiring harnesses.

okay so I just took the car for a spin and let it warm up. Got home and unplugged the MAF and it didn't stall itself out. When I went to plug it back in it kinda chugged a bit but still didn't stall. With it unplugged it started up fine..waiting a few minutes to go back out and try starting it again with the MAF unplugged and then again with it plugged in.

if it runs better with the maf unpluged chances are then it is eather dirty or shot, you can try to clean it but that is a temp fix and just best to replace it .

http://www.zzperformance.com/grand_prix/products1.php?id=378&catid=107

edit .. dont use that link u have a 97 thats for 99+

is it okay to drive with the maf unplugged? any way I can bypass it altogether?

unplugging it is a very temp fix and no there is no way you can buypass it because it moniters the amount of air that goes into the intake, by unpluging it it goes off of what the pcm says i think.... but you SHOULD NOT drive permanately without it if you order one and hook it up you mpg should improve as well because of proper readings

grrr...how did I get a bad one? OKay, so buy another one and try again...will do tomorrow then. Poor car!

you have allready replaced once ??

Check the MAF sensor connector for backed out terminals or poor wire to terminal connections. If it runs bad with the MAF plugged in, try wiggling the wire harness; make sure the TPS and MAP sensor connections are secure as well.

just to let you guys know, it is the fuel pump and leaking injectors. Mystery solved, but about 800 canadian to remedy the problem..too bad I couldn't find a good mechanic in the first place. Well at least the car has a lot of new parts. Getting fixed on Wednesday.