1992 F150 5.8 with AOD, had ton of idle issues, going up and down and rough acceleration, find EGR valve stuck open, got it shut, replaced IAC and the timing was off and the throttle wasn't closing all the way, replaced all that and truck runs alot better.. couple issues i still have. when i put it in park after driving it revs up to almost 2000 rpm, also revs when down shifting when coming to a stop, even idles at about 900-1000 but its steady unlike before..when shifting into OD i have to let off gas a bit...is this an engine or tranny issue?

 

Double check your work on the throttle body.
Look at the trans speed sensor cable, sensor and it's drive gear. The sensor has to signal the EEC what is happeing for road speed vs shifting and IAC control.
There is no other way for the EEC to know what is happening because the trans is controlled by a mechanical throttle controlled TV cable and the trans own internal govenor for shifting it'self.
Doesnot work like a later PCM controlled trans.