Originally Posted by rdharper

Ok. Make sure your throttle is returning all the way against the stops. The dashpot could prevent that (probably not as you had the symptom from the begining). I think the ECU is seeing the open condition, rather than the short, when your throttle is physically in the idle condition.

Had the same symptoms with mine. I ended up adjusting the TPS with the engine running. The idle position is a knife edge. What I did, maybe not the recommended method, was to loosen the adjust screws just enough such that I could move the adjust. You should see the low rpm condion, and, then the high rpm condition. What you want (this is counterintuitive), is the point where the high rpm case just barely is caught at physical idle. Tighten it down, and then continue to bring the rpm down just the way you did when the TPS was disconnected, with the TB idle adjust.

After a few such adjusts of the rpm, the surging should be reduced to less than a hundred around 800 rpm. Which is what you wanted, if memory serves.

May take multiple adjusts down (maybe the ECU relearning, whatever) over some period of time. This is what mine did. Surging at idle should continue to go down at the same time. Mine now sits at 800, and stays within a 100rpm band now. Also, and this may be coincidental, as other minor changes I made in the same time period, (mostly fluids) my mpg went up one or two mpg over the same period.