overdrive issue on automatic 97 3 series coupe

when driving the car will shift fine through 1,2,3 if the car is in the 3 position and will shift to od when manually put into D. if u put the car in D and drive it will start in 3rd or 4th. also runs rough when at a stop light. I think it may be a sensor like Throttle position or speed control or transmission control. I don't think its the tranny itself any input? Thanks Guys :banghead: