weaklink

OK my problem doesn't seem to be like the others I've read about. I don't have any trouble with cold idle. When I restart the car with the engine warm, the revs go to 3K for a bit then bounce from 1500 to 3000. I can put it into gear (I have an automatic) and it quits, but obviously I can't start it in gear. I have looked at the commander and the water temps are like 100-105, but they quickly fall to 88 or so. It only happens if the car is hot. If I restart it and the temps are near normal, then it doesn't do this so I feel like it is heat related. Any ideas? Will this hurt my engine? How do I stop it?