I too, am not totally convinced the pot is the problem. But for $40, why not try it, as you said.
Weirdest thing. I park my car and get 10% fixed koeo. When it's running I get a variation of readings around 10%. After it sits for about an hour I get 70% koeo.
Same here, to a T. My idle is fine as well.
If I am feeling better tomorrow (I have a nasty cold), I'll pull the potentiometer. I confess I am a little nevous about the process thoughas it sounds tricky, getting the position of the arm marked off and all.
Good luck to us.