All
At lower speeds the truck is a champ.
U joints are fine, no ice in the rims or brakes
At 55 mph it wants to shift and bucks and retards in the transmission. The engine is fine.
Is it a solenoid? If so, which one and how to repair link would be so helpful.
Thanks

2001 F350 Crew Cab V10 Automatic 135K not abused at all, just bought it, and flushed the transmission fluid with about 20 qts.

 

Are you certain all of this isn't centered more around misfires in the COP's?

Have you connected a scanner to it or does the MIL come on?

 

I can't think of a way the trans could do this. Investigate an engine miss as JWA said.

 

All
That was exactly what was wrong!!!
Coil Over Plug was shot on #4 drivers side
Plugs were ancient
Replaced boots and one coil and 10 plugs and she is a brand new machine.
Followed the very detailed instructions for spark plug replacement on this site. A MUST READ our you'll get dirt down the cylinders!
Took 2 hours
Also replaced the belt tensioner in 2 minutes. SWANKING like a pig.

You all have no idea how helpful this site is to me in the middle of no where North Pole Alaska. Thanks so much!