When the engine is hot and I'm cruising about 50-55 MPH I get a bucking sensation. If I increase the speed it stops until i resume cruising at about the same speed. It seems it happens as soon as it goes into O/D. At no other speeds does it do this. Does anyone have any thoughts about this. I called a few dealerships but they just said you have to bring it in. And fromn past experiances that means a min of $500. Any help is greatly appraciated.