Did a little searching but didn't come up with much on the site. Recently had the check engine light come on, ran up to Autozone and here are the codes...

PO102 MAF/VAF CKT.
LOW INPUT

PO107
MAP/BARO CKT.
LOW INPUT

PO108
MAP/BARO CKT.
HIGH INPUT

I don't really know where to look for info on any of these and the Autozone guy was pretty much useless. The car's a '00 Grand Prix GT. It had been running perfectly fine up until yesterday afternoon. It will occassionally die at stops or run sputter really bad then get better. Ran perfectly fine all morning but started up again this afternoon on the way home. Nothing has been done to the car other than an oil change last saturday.

Welcome to the forum! I'd start with the lowest number code first; check the air filter, and air intake duct clamp(s). If the filter looks okay and the clamps are secure, check for vacuum leaks, and repair.
Sometimes during an oil change, the guys check the air filter, and don't secure the air filter housing properly. If all looks okay, start the engine, and wiggle the MAF sensor wire harness; see if you can recreate the idle problem. Also, check for any unplugged sensor connectors. If it turns out to be a bad MAF sensor, it may be causing false MAP sensor codes, due to the idle problem. Good luck!

Changed the air filter, checked for broken/cracked/disconnected vacuum lines and found none and played with the connection to the MAF sensor and still the same. Assuming the sensor has gone out and went to A.Z and they're asking 139 + 89 core. Would going to a junk yard be better and finding a used 1?

I have the same engine code P0108, and my MAP sensor is completely shot. I took a look and it's snapped in half. I'm waiting for a warmer day to fix it though, so no dice yet. I'm sure though that replacing the MAP sensor will fix it.

(you might check your MAP sensor, it's located on the left hand side of the upper intake manifold)

I'll check that...does your car run decent in some instances but seem like its struggling in others? This morning started up fine in freezing conditions and ran find for about 10 minutes but after warming up started running really sluggish.

If you've never had a problem while the engine is cold, I would suspect the IAC.... If you know anyone else with a GP, you can start swapping parts until you find the culprit...

Thats the thing...it ran pretty bad last night when I returned home and I expected it to act up starting it up 1st thing this morning but was surprised when it idled and ran fine for a bit.

And unfortunately I don't have anyone around me with a GP

Hate to say it but it looks like its trial and error time. It can be any of the 3 things....

Merely an update and another question. Replaced the MAF Sensor friday, and the car was perfect. The Service Engine Soon light went out on its on but came back on 2 days later. Went to Autozone and had them clear it and it again came on on Sunday but went back off today while driving home from work. About 10 minutes into the drive...it went off. Is this normal? Should I disconnect the battery for a bit to maybe completely reset the system?

I'm kind of lost as to why it turned itself off, back on and then off again today....

Well I don't know if it is this, but the CPS sensor sounds like the problem. My check engine light would come on after my car would stall out occasionally while driving or at lights. And it would also run rough too. Got that fixed and it solved the problems, but I also got a new MAF sensor and new fuel crap that contributed to the problem, so I would think that you have either of the two and or both in the worst case scenario.

Since you've already replaced the MAF sensor, I would suggest you disconnect the battery for 10 minutes, then road test the car. Be sure to shut the engine off for at least two minutes. Do this twice. If the SES light comes on, record any codes that come back, and let us know what you find.

Recently had the SES light come back on.

Decided to head the AZ and got a new PCV valve, and fuel filter to maybe help resolve the issue without having to do another major purchase to fix. Went and removed the MAP sensor and noticed some oil on the bottom of the sensor. Removed the mount/spring to get to the PCV valve and the entire valve was covered in oil, top and bottom. Not 100% sure if its supposed to be like this. Removed the O-ring and seemed to be ok but with a little build up on one side. Is this normal? If not this may be the reason why the MAP sensor's gone out, with oil getting to it??? Thanks in advance...this is starting to test my patience