4.0 idle

I have a stock 95 explorer with id say about 250,000 miles on it. my problem is when the truck has been parked and i go to start it i have to keep my foot on the gas to keep it running, i dont have to pump the gas or floor it, just enough to keep it at an idle. After i get in and take it down...

yes, i am a newbie to explorers. but not to working on cars, i have restoed my 80 stang. i havent dealt the a injected car yet, so im reaching out..lol when you start it up its fine, then you can drive around all day. but when you come to a stop in park, it starts to idle rough, like its...