b2600i idle fluctuates w clutch pushed in

[bhowell]

1990 B2600i 169K miles I bought the truck with a blown heat gasket. I just took care of a head and head gasket issue and replaced radiator, water pump, thermostat.

Truck runs, however once it warms up it seems to idle fine, but if you push in the clutch the rpms fluctuate between 700 and 1500.

I've pulled the ecm and do not see any issues on the board.


What else should I consider?


Thanks

 

[theoldraker]

I have an automatic and had the same problem, (crazy idle when stationary) when I bought the truck. I got a $1.00 toothbrush, and some throttle body cleaner, cleaned the throttle body, and it idles fine now. Might wanna try that.

 

[SenorNoob]

Does the tach look like it's waving at you? LOL My 4.0 swap does the same thing, but only if you press the clutch in while going down the road. I always figured it was the fact that I don't have the Neutral switch connected on the transmission. Honestly never bothered me enough to make me look farther.