I bought a 1990 ford f150 with a 5.o engine and automatic with o.d. button on dash. At 35 -45 mph I get the shaking until I give it the gas. I know the o.d. is kicking in because of rpms dropping to 1000 plus. That's when the ride is rough if I stay in that window which I have to driving around town. Trans. shop told me everything checks fine and that's just the way this model is made. How can I fix this problem? Love this truck but hate this condition. Any help would be appreciated!

 

You could always place the OD in OD OFF when riding in that MPH range. Once you get on the open road you can depress the button to allow it to go into OD.