dlbrenneman

One thing I forgot to mention. This problem only happens at start up. That is while driving the idle doesn't increase. Whatever it does when you start it is what you have to live with. Seems to me when talking about sensors and such there is an open loop vs closed loop. I need help with this.Start this thing ten times and it won't do the same thing twice.

Replaced map sensor today. Still no good. Starts pretty decent the first time but the second or third time you can bet it will go to two thousand or better. Presently it idles back to normal after about thirty seconds but you can bet one day it won't. Might start on cruiser's renix tips. Sounds like he's been around a 4.0 a few times. Thanks for the link. Lots of good info.

I have a 1990 comanche,4.0,4 wheel drive,automatic. 64,00 miles on the odometer. Last year heading for home after hunting the idle shot up to about three thousand and stuck. Burnt the brakes off but got it home. Bought another truck but would like to drive this also. Did all the easy stuff. Cleaned T B. ,replaced I. A. C. ,TPS. To no avail. Thing won't do the same thing twice. Idles down now but still revs to 2000 at start-up and sometimes stays there too long. No vac leaks that I can find. Truck has had an exhaust leak at the manifold since i bought it. We all know about the manifolds cracking. Wold loose or missing bolts at the intake do this?