i have a 88 iroc-z 5.7 i can not figure out what is going on with it everyonce in a while she would hold an idle fine and then stop the next time i started it i have advance than reduce the timing to see if that would help and i have also changed the tps sensor and somebody had asked me to clean the idle air controll sensor i cleaned it didnt work so i replaced it and now she will not hold an idle at all if somebody has anything to help please let me know thanks bryan

 

that is a frustrating problem. i had something very similar happen to me on my 87 iroc 350 tpi. i tried everything you mentioned above with no results. finally i figured out that it was a vaccum line cracked. it was the one that ran over from by the brake booster not from the booster itself. under the intake near the distributor and made a sharp upward turn up to the intake where it plugged onto a fitting on the intake it will be on the left near the remote mount coil. it is a 7/32 vaccum line. mine cracked right in the upward bend. i replaced it and it cured the problem. if not be sure to check all the vaccum lines. hope this helps you.

 

Thanks alot i will try that today when i get home but see i finally got her to hold an idle and she will for about 4 or five days and then drop it again and i unplug the tps sensor and the idle air controll and start it 2 or 3 times and plug them back in and she starts up and idles

 

Your welcome man, let me know if that helps. If not I'll do some more head scratching and see if I can figure something out.