weird idle?

[97 gst turbooo]

Alright so this has been going on for a little while and its driving me crazy. Ive boost leaked checked my car mulitple times and theres no leaks. My car will start up cold idle around 15-1200 just fine around 19-20vac. Then it idles at normal 750 but only has 15-16vac. But when im driving its fine but sometimes when im in neutral at a stop it will idle at 1500 constant and then sometimes at 750 it idles between 750-1800 and its all at random and different rpm's. What could cause this problem? Any help is appreicaited. Also tonight my car starts up rough,cel comes on for CAS. Unclipped and reconnected and it started fine. This has happened twice and another time engine just cranked and cranked but wouldnt start, i did the same thing and it fired up. Thanks for any help guys.

 

[bluetlr2001]

It sounds like your cas is starting to go bad. But the idle may be from your tps. Theres a way to test it buti cant remember how. Also you might want to adjsut your tps. heres a link on how to adjust it. If when your adjusting it you can also test it with these directions. It says to do it with the throttle body off the car but if you can get to the lower bolt with it on the car it uses a phillips screw or its better if you can get a 8mm socket on it. I done mine with it on the car.

TPS Adjustment

 

[97 gst turbooo]

i figured it was going out. I have a 6 bolt head here with 40k on it so i might use that CAS. And thanks for the help ill have to try the tps this weekend. Becuase running preium gas at $3.35 a gallon im sick of wasting money buy ideling crazyyy.