22re 91 pickup. 5 speed.


Generally runs great. Starts fine. cold idle works great.

But..

When the truck warms up, and the engine is not under load - idling or with the clutch in or in neutral, the idle will surge quite a bit back and forth back and forth (no idea of the rpms because there is no tach)

Another thing to note is the truck is actually easier to start when COLD, and can take a little while to turn over after it has warmed up. Not sure if this is related.

Seems like all the hoses are in good shape, and there is good vacuum all around. The engine was just rebuilt. From what I have read in other posts my problem is either the TPS or the Idle control valve. Is this correct?

Which one seems to be most likely in this case? Thanks.