I'm very interested in the answer to Rebus's Question? The truck is a 1989 with auto and 460 and should involve one of the sensors on the fuel injection system. It should not require any changes other that a simple part replacement. I've had the same question and pulled codes, but no codes. The question from Rebus is:

I'm having a power loss problem on a bone stock 1989 E-350 with 460CI, C6 trans. It runs well on it's own, but when pulling a trailer it falls apart. With the heavier load, stepping into the throttle results in drastic power loss and it seems to misfire. Heat makes it worse. It runs better when cold out. The following has been done:

New plugs, rotor, cap, wires, fuel filter, fuel pump (pressures check fine on the fuel rail), muffler (cat. checks fine), ign. module, EGR valve + controller, and computer. Ran some gas additive cleaner through it. The only codes it registered was the EGR valve.

Pull the plugs after they've run a while under these conditions and they look clean.

Ideas?

I've been watching this one for quite awhile, but there have been no good answers. Surely someone here has some experience with this same issue.

What is the answer....