Well I've been in Phoenix for two weeks now and I've got till the end of the month before my Missouri tabs expire. I've got to run the truck through emissions and I'm having a bit of a problem. My truck is not idleing properly. It will do one of two things, either it will idle at 2500 or it will rev from 900 to 1250 drop suddenly and start over. No matter what it is doing if I jump out and force the throttle all the way closed it will idle properly. I used a shim under the throttle return spring to tighten it up and that gets rid of the 2500 idle but the revving is still there. I would prefer to find the true cause of the problem rather than a mickey mouse solution. Any ideas?

I already checked the TPS is seems to check out, and I also cleaned the TB.