when you say "TP sensor" are you referring to the foot pedal postion sensor or the throttle body?
my w.a.g. (and I have looked at a few of these over the years) is a bad (stuck) throttle body or bad computer. this truck should ONLY idle if the foot pedal position sensor is out of whack. you may have a bunch of crud built up inside the throttle body.
are the 2 vac lines on in the correct places(the bottom one goes to the little computer box and the top one to the distributor) do you have the lines to the fuel trim valve correct? one that looks like a tee, is not a tee)