Hey Dave; I thought about the lack of VSS a few times - but I have set any tune values to 0 as far as throttle follower steps, MPH to enable Idle or large IAC error etc.
Not discounting anyone's thoughts, but riddle me this: what it does is - Truck in Park, idling - closed loop, holding desired idle RPM in park (IAC counts around 18 = 750 RPM) - pull it into gear and let the ECU raise IAC counts to get back to desired CL idle RPM (Now prob 34 counts to get back to 750 RPM) I put it back into Park (yes ony - P/N switch works and I can see it change state with my scanner) and then the idle seems to hang at anywhere from 950-1000 RPM - the IAC counts are higher than at desired RPM (usually stay at 34-ish), so the ECU is commanding the new idle speed; since I haven't moved the truck, a VSS signal shouldn't matter - otherwise a stock GM TBI would act the same way if you pulled it into gear, idled for a few seconds sitting still and put it back into park, right?
I did find a scaler in the tune labelled Min TPS % which was set at 25% - now that I'm at 0.50V TPS at idle that puts me at 10% - I changed the value to 10% and will see what happens tomorrow. Thanks for any and all suggestions so far... I wouldn't give a rats a** about the idle issue if it wasn't for the truck having a doubler transfer case with a redic amount of gear reduction, and my tendency to flop the thing on it's side from time to time on the rocks. A nice predictable low idle would be very nice :)