2001 Ford Explorer shifting problems ... ?

[misspebbles71]

I have a 2001 Ford Explorer XLT, 4x4. I just strted experiencing something weird this winter. When I shifted into Drive from Park and took off, about a few minutes after driving, my engine sounded like it was revving but not shifting, (like being stuck in first gear on a standard car). It wasn't really gaining any speed. This happened 2 seperate times. It seems like it only happens when my vehicle is cold or has been sitting a long time.
I told my boyfriend about it and he said it could be happening because I wasn't letting me vehicle warm up in the morning before taking off for work. So, I started letting my Expl warm up at least 15 minutes every morning.
Well this past weekend we went to our cabin and the vehicle sat most of the day (in the cold) while we cut wood. When it was time to leave (he was driving) after starting the Expl and putting it into Drive, we took off. About 5 minutes after driving it started chugging and slowing down and not shifting. I told him what I did before was to pull over, shift back into park and then back to drive. That usually solved the problem for me. He did that and then it was fine the whole way home. Thank God because we were about an hour away from home, but now I'm really worried.

So, are there any recalls or transmission problems I should be aware of for my year of vehicle? Is there anything I can do to correct this problem or does anyone have any advice for me? Please help!!!