Well, this has been an issue for a short while now and I'm interesting in selling my car and want to know how serious it is: When the car is cold it won't shift into overdrive, but I'm thinking this is by design. However, once everything is warmed up, it occasionally won't get into OD after coming from a stop. When this happens it drives normally in 3rd gear and then after maybe a half a mile it'll go into overdrive. It's fairly infrequent.

Trans fluid looks good and all other gears work fine.

Ideas?