I have a suncoast tranny with 4000 miles on it. Everthing worked great up until a few weeks back.

when it gets to 45 mph it bucks in and out of overdrive until I romp on it and get to 53 mph or so.

I bought a new apps and calibrated it...no change, fluid level is fine

Once my tranny temp gets over 140 degrees there is no problem


any ideas?

 

fixed...tried the ground off number 4 pin and that made the throttle rev randomly so I undid that mess.

cleaned the battery terminals with a wire brush and the truck works great.

 

There's a very good chance your ground supply to the apps is got to high reisitance.