i had a problem the mechanic said the timing wasnt advancing he checked everything out and said it was the prom chip i got a new one set the timing reset the pc and the car was very crisp and faster than it was before,now it runs fast most of the time but once in a while it seems to get slow again i dont understand is it my distributor? i checked the timing and it is advancing so i dont understand why it gets slow sometimes and runs good most of the time. has anyone else had this problem? i am getting very frustrated i allmost want to sell it when it gets slow but when it runs good i want to keep it some please help? sorry so long of a post.

 

I'm assuming that your car is an 87 GTA?
I would check to make sure there are no vacuum lines leaking. There is also a TPS, and should be an IAC motor too. If any of these aren't working correctly, then you can get problems such as to what you are describing.
Are you getting an SES (check engine) light?
If you want to check to a vacuum leak, take a length of rubber hose, and hold it to your ear while the car is running. Move the hose around in the engine bay around the vacuum lines, listening for a whistling noise.
Good luck, and don't sell the car. They are getting harder and harder to find every day.

 

its a 1989 GTA 350 TPI,i set the TPS at 0.54 and IAC seems fine i am not getting any codes i will check for vaccum leaks thank you if anyone hasd any other ideas let me know. i ran it this morning and it seemed qiuck but then today after work it was very doggie again.

 

Oh yeah, I also read somewhere that you can get a can of brake parts cleaner and spray around the intake area and vacuum lines...if the car's idle starts to go up, then that is where you have a vacuum leak. Never tried it personally though, but it makes sense to me.

 

I don't know about you guys but spraying crap all over my motor in the hopes of finding a vacuum leak doesn't sound like the best idea. You can put a vacuum gauge on it to check vacuum (there only $20), I would also check your fuel pressure when it acts up and see if your losing pressure during those instances, possibly a pump acting up or regulator failing. A semiclogged catalytic converter can also cause intermittent power loss.