on my 85 t/a 305 tpi when i start the car cold (i.e. in the a.m.) it idles fine-right where it should- but if i drive it somewhere and start it when its still relatively warm (like at school maybe 6-7 hours later) or any sooner and the idle goes right to and stays at about 1500 rpm if i try to kick down the idle it will either stay the same or go up slightly. but if i wait until the next morning it is fine again. when i look under the hood i can see bubbles rising up through the tube on the inner side of the coolant bottle, anybody know what this could be? i was thinking maybe the thermostat could be bad but im not exactly sure, it was a small problem but is now more frequent and i hate putting the car into gear at that high of an rpm. thanks in advance for your help

 

The "obvious" culprit is the IAC. It's never a bad idea to remove and clean it, as well as cleaning the throttle body bores and plates.

The other points to inspect are potential sources of vacuum leaks, such as the PCV, all hoses, brake power booster, EGR, gaskets, and injector O rings.

 

um

bubbles in the tank means you need to have better gauges first of all

you are overheating