91 PU 22re Manual 285k on the odometer

Took apart and cleaned the intake manifold about 2 months ago, at the same time replaced the t-stat.

At 1st start up the truck runs fine. For some reason after just a few minutes of running and just before the t-stat opens up, it starts to surge and stutter for a bit, and then as soon as the t-stat opens up it's a night and day difference; it smooths out and runs much better! Didn't do it before the cleaning, so I feel it's related, but idk.

The only thing I can think of are one or both the 2 sensors on the front of the manifold are bad (I know one's for the ECU and the other's for the cold start valve), but could this be an air pocket in the system as well? Would throwing in a cooler t-stat stop this? Anyone else ever had this accur?

Thanks in advance guys!

 

Park on a small incline, take off the rad cap and run the engine... Stay clear of the rad opening.. If there are any air pockets it'll "burp" and they'll be done away with..

Try running it without the t-stat for a bit. See if there's any difference.

You won't hurt anything.

 

ya sounds like air in the cooling system. Your cold idle plunger is not closing causing the idle to be to high in open loop, thus the surging. I would also check your TPS out just to be sure it is working properly.

 

yeah, the TPS is set up right; made sure I did that when I threw it all back together, but I'll burp the system again. did after I put everything back together, but I guess I didn't get all the air out

thanks guys, I'll let you know how it works out!

 

Can you explain the cold idle plunger, where it is and all that? Just never heard of that on a 22R-E. Unless you are talking about the aux air valve/idle air control/whatever-it's-called under the throttle body, then never mind.

 

That's what he's talking about....

 

That's the only thing that made sense, just wanted to make sure. :-)