My 1991 F150 5.0 Lariat 4x4 bucks when outside temperature is warm
During the warmer months here in Virginia, my 1991 F150 surges (feels like someone ran into the back of me) when it shifts gears. During the colder temperatures the vehicle shifts smoothly. (Automatic Transmission). This condition only occurs during the warmer months. Taken it to several places and no one can give me an answer. What's up?