Engine wants stall when warm



91 S-10, 2.5 “A” 4-cyl. idles fine cold, but wants to stall every 4-5 seconds. It then catches itself & resumes a good idle. Runs fine at highway speed. IAC, air charge temp & coolant temp sensors, & fuel pressure regulator diaphragm replaced. Trouble code reads 15. Only 51000 mi. Has strong unburnt fuel odor. dinsk451


I think code 15 is for the coolant temp sensor. That would make perfect sense since the basic symptoms you describe mean that the truck is running rich - after you start it up it never backs the “choke” off b/c the engine computer still thinks that the engine is cold.

Is the truck running cool? If your gauge is in good order you can tell from that, and it would mean that you probably need to replace the thermostat. But you should also test the coolant temp sensor and replace it if it isn’t within spec.


Gauge works fine(about 180 degrees). Blows warm air when warm. Changed last coolant temp sensor in the thermostat housing today. (Previously changed temp sensor in block). Cleared code & it has not recurred after two trips. Still wants to stall.


Since last post have replaced TPS, cap, rotor, wires, & fuel filter. No trouble code or raw fuel smell. It has never run better but warm stall condition persists. dinsk451