1988 K2500 intermittent idle

Have a 1988 K2500, and it is idling erraticly until the engine is warmed up. 350 with TBFI....idle is up and down until engine is warmed up for about 5 minutes or so.....

Thoughts on possible causes?

I have same truck, motor, complaint. Im thinking its the FPR in the TBI unit

^^^

Idle air control valve it's about $35 at autoparts store and can be changed in about 10 min with a pair of vise grips.

Idle air control valve it's about $35 at autoparts store and can be changed in about 10 min with a pair of vise grips.

Nope.

I take it you've tried that, quaddriver?

Hoping someone may know exactly what the deal is, before any money is spent ...

It could also be the Coolant temp sensor on the front of the motor next to the thermostat. The ecm monitors the coolant temp and sets the idle speed through the IAC accordingly. (higher cold, lower warm)

Been there done that also. No SES and getting O2S crosscounts.

thats why I am leaning towards the FPR in the TBI unit. At speed and when warm she is fine. but cold idle she is very rich out the pipe, I am thinking it is loading up.