Totally agree on that FridgeFreezer. That's why I switch the 4.2 plenum that has the round TPS [these are absolutely totally unreliable] to a 4.0 plenum that has a bosch TPS and the new GM style flat connector idle valve.
I just feel that the truck is more responsive on TPS rather than manifold vacuum..
As for the idle valve, I would say that PWM is probably the way to go... the stepper is nerver quite right.. some idle is at 900 sometime at 1000.. all in all, I think you guys are right, if I had to do it again, I'd go MS1 extra...