1996 Bronco, 5. 8, auto/E4OD, about 200k. Truck used to idle ~500-600 rpm. A few days ago the truck began idling at ~1000 rpm even after engine warmed up. The truck idles high while coasting, at 1000 rpm, and sometimes after higher revs only slows to ~1500 rpm without having a foot on the gas pedal. Other times will be coasting at about 1000 rpm and it will rise to 1500 and stay there on its own. Gets more prevalent after getting up to operating temperature. Truck would have erratic lag-response to gas from stop - no response to initial gas pedal travel, then immediate response past a certain point in travel. Torque converter would engage/disengage while driving at constant speed and in middle of respective gear range (not near shift point), correspondingly RPM would jump around. Truck does not want to seem to shift below 2200-2500 rpms - engine has to wind way out before transmission drops into next gear: most pronounced in the 1-2 shift, better between 2-3 and 3-OD. I tested the TPS and it showed erratic resistance on analog meter during throttle valve travel - was lower at idle, then would increase in resistance as throttle traveled to about 25% throttle, then would evenly drop in resistance up to WOT. Pattern was repeated in closing travel. I figured it was a bad spot in the "90% of your driving done here" range. Removed throttle body and replaced TPS. Cleaned throttle body while it was out with throttle body, not carb, cleaner. Reinstalled everything, I did not replace the throttle body to manifold gasket but did reinstall bolts to factory torque spec. Manually cleaned IAC while it was out and made sure gasket was in good shape. Also cleaned the MAF with MAF cleaner while the air intake was disassembled. Started truck - still idles at about 1000 rpm. I took it on a quick test drive, torque converter disengagement and associated engine revving was corrected as well as gas response. Truck still didn't want to shift below ~2200-2500 rpm and idled high. Truck idle drops to about 400 rpm when IAC is unplugged. When plugged back in rpm raises again to 1000 rpm. Iterated several times so doesn't seem to be a stuck IAC or bad motor. I've not done an in-depth check but there are no obvious/whistling vacuum leaks. Not sure what to look at next - PCV? Coolant Temperature sensor? Any help is appreciated!!