High I just put an L35 in my 1991 4door blazer. It seams to run ok other than a rolling idle sometimes and when accelerating. I did replace the regulator and put the correct fuel pump in when I did the swap. It doesnt seem to surge as much when it's cold.

 

Did you check/clean the EGR valve before you dropped in the engine?

 

When cold the IAG controls idle, once it warms up the TPS controls idle. Verify they are both working properly.

 

The IAC is in control of idle speed all of the time. The TPS is just a sensor and cannot physically move the throttle.

With a rolling idle, I would tend to agree with Leeann about the EGR.

 

I have had a problem with carbon getting stuck in the pintle of the EGR. I just take it off push the pintle the get the carbon out. Then seems to be fine. Also I do not have any DTCs in the ECM

 

I think I found the problem. The IAC valveseems to be acting slowly turning on and off.

 

IT WAS THE HEATED O2 SENSOR!!! thanks for your help

 

i was wrong, not the o2, not the iac.