'96 GMC idling high...again.

[cam.man67]

Last year, my GMC wouldn't idle at less than 1500rpm. After much testing and some helpful advice on here, I wound up discovering a faulty TPS. No engine codes prior to the fix, and afterwards the truck idled back down to 6-700. Perfect.

Now, the high idle is back. I assumed that because I didn't buy a super high quality TPS that it already failed. Replaced it with a Delco TPS this morning. But the idle hasn't come down. No codes again, had it in the shop last week for a random miss, that wound up being a miss on #6 because of a bad plug wire. I ran it for about 15 minutes to make sure the truck warmed up, and after shooting into gear and back into park, the idle cane to about 1100. In addition to the high idle, when I put it in gear, the motor revs to about 1800 before getting into gear. In gear with a foot on the brake the idle is 900-1000. Help!