I'm working on a 1996 Thunderbird with the 4.6 engine. Transmission was shifting fine than all of a sudden with would not go past second gear. 1-2 shift a good with no lag or slipping. I have engine braking in manual 1,along with manual 2. From a take off the car with go 1-2 normally than hold 2nd until 36-37mph and than neutral out. If I engage manual second it kicks back into 2nd. If I keep it in drive while its neutraling out I can get second gear by rasing the rpm but it seem to slide than bump not bang back into 2nd. Also the over drive light does not have any effect during the neutraling not during acceleration. It wont light up with KOEO nor KOER. I have checked the fluid and it seems fine.