First of, this is my 1st post and I just became an owner of a 98 GT - man i love this car...

I took my car to "jiffylube" over the weekend (yes, i still pay to get the oil changed but eventually I would like to do it myself). Anyway, the previous owner had taken the car to JL ever since he bought it back in 11/97. I was told that the air filter should be replaced cause it was a bit dirty although it was not a MUST but the guy said that by the next oil change it should be replaced. After they changed my oil and did a transmission svc. i was on my way home...
I'm hearing a hollow noise when i accelerate. i did not hear this before i took the car in for service. when i start my car, everything sounds ok, when i accelerate i hear this noise, i souds like it's coming from the air intake area. i hear this noise when i step on the accelerator, not just tap it, but when i really push the accelerator. Also, i have noticed that when i'm driving and i'm going to make a lane change and need to accelerate fast, the car hesitates and you can really "feel" the shifting in gears. Could they have not installed the air filter the right way (for the noise i'm hearing)? and as for the hesitation, could they have done something wrong when doing the transmission srv?

I'm not a car mechanic so i'm really sorry if my description of the problem is very plain.

thanks for all your help in advance.

As far as the hollow noise is concerned, I think the only thing that would make it sound more "hollow" with the air cleaner installation is to not install and air cleaner. It is fairly easy to check if you have one. Just undo the 2 clips at the top of the airbox and pull back a little (the air duct will be in the way but a little space is all you need). If the air cleaner is in there, and the hoses are on and the box is shut, then they probably did OK. I would need more information for another guess.
As far as the transmission is concerned, you may want to check the trans oil level, and see if the fluid is burned or has excessive clutch material in the fluid.
1) Drive the car a few miles and warm up the car.
2) Leave the car idleing in Park on level ground.
3) Get a rag and pull the dipstick. Clean the dipstick and put it back in.
4) Pull the dipstick out again and read the level. Remember that it does not take a lot of transmission fluid to raise the level. Too much transmission fluid is real bad because when it gets hot it could expand up the drain tub, go on to the exhast manifold, catch fire, and turn your car into one of those black rectangles are found on the side of the road going to Las Vegas. (Yes, one of the Black Rectangles in Death Valley is mine from a failed prototype I was testing many years ago, so I know this all too well).
5) While you looking at the fluid, It should be red in color. A dark brown color would indicate burned fluid or clutch material in the fluid. Dark Brown is bad, take it to a transmission repair guy (ask around for a good one, not AAMCO).

Another issue could be the PWM Band Apply solenoid. You would probably get a code (Check Engine Light) if this slipped real bad. Don't worry about this until you check the above.

Also, please check out the "Grand Prix Problems" button on this website. It has an excellent source of information with a Transmission specific section.

Finally, Welcome to the site!

Hey Brad97GTP, thanks for your suggestions. I'll look into that. I did stop by Jiffylube again today to have them recheck the transmission oil level and it was under the recommended level so they added a bit more. I told them about the air filter issue, they re-checked it and everything was installed the way it should have.
I forgot to mentions this before: my alternator just got replaced (couple of days ago - after the jiffylube experience). can the alternator replacement have any of the issues i'm currently having?

Thanks again everyone.