It's 200k. I'm starting to fear the headgasket as well... I replaced the cap, rotor, and the rest of the plugs with no noticeable change in idle, though this may have fixed the surging with throttle steady. I then set the valves to .007/.011 (Engine was only warm at this point) and now the thing won't idle at all, even with the idle adjustment screw nearly all the way out. Disconnected EGR to make sure it wasn't pulling way more vacuum and opening that thing but no change. I'm gonna check the TPS again and then...???

But if the TPS is putting out the proper resistance (200-800 ohms) at idle shouldn't that be fine? Won't that at least put the computer in idle mode?