Weird Idling

I had something odd happen today. I was sitting in a drive thru in park with the truck running. As soon as I put it in drive to leave the rpm's jump up to like 2000 and the truck lurched forward. I slam on the brakes and put it in neutral. Then the rpm's drop down below 500 and the engine starts spitting and sputtering then levels out at about 1000 rpm's. I limped it over to a parking spot and killed the engine. I popped the hood and didn't see anything out of the ordinary. Then I started it back up and it idled like normal and I drove it home with no problems. Anyone have any idea what would cause that? Should I be worried? Could that be the PCM or a sensor somewhere?

might be some build up on throttle body or iac sicky, start with cleaning throttle body.