1994 Accord Wagon EX – Unusual idle

Recently replaced the radiator on my 1994 Accord Ex Wagon. Car idles fine when in park and even after gets up to temperature while in park. If you put it into drive its fine as well for idling, It does have a thump as you shift into gear (P-R, R-N, N-D) but I think thats possibly a low fluid situation or just could be the transmission showing its 236k. However after you’ve driven it a good bit, and put it back into park, it either idles at 1500 or idles up and down between 1000-1500. Waterpump and TB were done about 20k ago. Burped the radiator after replacing it by using the valve on the thermostat housing. Not sure what is causing this weirdness that only occurs after driving it. I checked and nothing is tugging on the throttle cable and it appears to be parked against its stop. As a side note, the car sat for 11 monthes (With me starting it about once a month and moving it around a bit while I worked on the body damage). I cleaned the IACV around the time the TB was done in addition to the EGR tray ontop of the intake manifold. So any help would be appreciated.