[RRclassic95]

1995 classic cranks and runs great when cold, but after running for about 30min and letting it sit for about 20 minutes it has a rough idle for about 10-15secs. after that it clears up and runs great again. I have replaced the fuel pump, filter, plug wires ,plugs and TPS sensor. I checked fuel pressure on the rail and it holds 38psi for 22 minutes after shut off and then drops to 28psi after an hour. I believe that rules out leaking injectors but I’m not a mechanic. Looking for any suggestions.
Thanks!

 

[msurover]

Check your coolant temp sensor and the wiring connected to it. A bad or failing sensor could cause this. In my case, the wiring to the connector had developed cracks up in the loom and would short out intermittently. Check and clean the stepper motor on the intake as well. It controls idle.

 

[Classicpain]

Check your coolant temp sensor and the wiring connected to it. A bad or failing sensor could cause this.

Where is the coolant temp sensor located?

 

[95classiclwb]

two lead connector similar to that of the injector, located near the upper water jacket before the thermostat.

 

[RRclassic95]

Update. Thanks for all the help. It’s turned out to be a broken wire inside the connector to the fuel temp sensor.