Okay here is the problem...hopefully someone can help! I have a 99 Pontiac Montana...a couple days ago while driving slowly in a parking lot I accidentally threw the gear shifter up, I immediately put in back into drive...Well it drove fine for the past 2 days and then today I drove it probably 60 miles...it drove fine..no problems. I stopped in a parking lot for about 45 minutes, went back out and it wouldn't shift into drive or 3rd. It shifted fine into 2nd and 1st. I had no options other than to drive it and try to make it somewhere. I drove in 1st then shifted to 2nd and tried to shift up and while driving it will shift to 3rd and D. If I had to slow down it would not rev up in drive or 3rd. Anybody have any ideas as to what this could be.Feel free to ask any questions as I will promptly answer.