Ok, I got a bit of an issue with the idle on my 1992 4.9 5spd 4x4 with 144k...

First off, and least annoying, when I start it cold: she revs normally, 1500 for a few seconds, slowly drops to 1000, but then plummets to 500 before rebounding to 800ish (normal for cold).

My biggest issue: when driving and going to shift or stop, punch the clutch in, and the revs stay up around 2000 rpm. It will usually hang there for a few seconds when stopping, then settle back to 700. With it being an i6, the idle hanging up also gets rid of engine braking and occasionally makes it gain speed all on its own.

Question is, what is causing this? Mainly the driving issue.
- I've taken iac off, cleaned and tested and it seems fine. I'll replace it anyway tomorrow.
- Already tried a new throttle position sensor, no change.
- No vacuum leaks (23in/hg steady at idle, propane tested, fixed a small one).
- Throttle cable and throttle body operate smoothly and are clean.
- No codes both koeo and koer.

Anybody got any ideas where to look next? This is driving me insane.

Thanks in advance,
Bob