High Idle

When I start my Bronco it idles up real high. Have to hit the gas to get it to idle back. But when I put it in drive it Idles back up. I cleaned the Air Bypass unit that helped some. But it does it from time to time still. Any suggestions?

what year? I am assuming this is carbureted. See if the choke is opening. Might have to get new heat tube things, or just go with a manual choke, can't go wrong manual.

It is an 88. But it is fuel injected.

Check the intake temp sensor and the temp sending unit.