i don't know whats wrong with my 88 gt 5.0 the motor is 86 though. When i start the car its fine but as soon as i give the car gas the check engine light turns on and when i let off the gas it has a very bad idle it goes up and down for a while just wanting to turn off and sometimes it does but when it doesn't it idle?s rough till the check engine light turns off and then it idle normal again till i give it gas again. I already changed the idle air control valve. thanks hopefully someone could help me

 

Did you check your TPS sensor? Check for vac leaks too. Also check your MAF sensor (also clean up the sensor sensing wires too, use the MAF air cleaner).

 

ya i changed changed tps sensor. i will check out the maf today but how do i check for vaccum leaks?

 

lol..slapping parts and you have a CEL on?? RUN a koeo/koer test and see what codes exist, do this before doing anything else , otherwise you're throwing dats in a dark room

 

how do i do that test koeo/koer test?

 

OMG, I didnt see that you have CEL going on, dude, thats the first thing you check on first then run diagnostics, then go through the list and eliminate/fix them. There is methods to run the KOEO tests. If you cant find the procedure here, go to:
SBFtech.com
And do reading there, if you cant still find it look up Joel.
Dont give up, keep at it........