85 302 idle issues

so a few days ago i was at the lake and wile driving across some sand sunk the bronco it was there for a day until a tow truck pulled it out the next day but ever sence we got it out the idle is at 2000rpm and jerks into gear(its auto). its an 85 with the 302 and i tried the unplugging the IAC wile running but the idle didnt change i dont know much about the truck just picked it up some any help is awesome thanx