Archived 1992 with a low idle issue

[Develdog1106]

I have a 92/auto that runs perfect when cold. Once the truck gets to operating temp, the idle drops way down when stopped and in gear- it feels like the torque converter is trying to lock up (I know that's not what the problem is, just what it feels like). When I take off from a stop, it feels like the truck is dragging a battleship anchor for a couple seconds, belching a lot of black smoke, and then takes off like a scalded cat. When stopped and I put it in neutral, it idles perfect. There are several threads with similar, but not identical, problems; this is what I've done so far:



-Transmission filter and flush (done every year with full synthetic)

-TPS checked, good

-Computer swapped with a known good spare one I have

-External 12v applied to KSB (and tried removing the wire also)

-Lift pump replaced (from Cummins)

-Injectors bled (twice)



Everything I've done so far has made absolutely no difference. I did stop by a local diesel performance shop and explained the problem to him. He had a quick look at the truck and assured me it wasn't a pump problem.



Any insight and/or help would be greatly appreciated!

 

[Develdog1106]

Thought it might be interesting to note that the truck seems like it has more power since this problem started, and it gets 1 1/2 mpg's more! (?)