I have a 2001 F350 with 7.3 Diesel and 4R100 Auto Transmission, it has started to act weird
seems like it is shifting in and out of overdrive or maybe the converter is locking and unlocking, when you cruise down the road at a steady speed while in 4th gear the truck suddenly seems like it's downshifting, the RPMs wil suddenly shoot up and then return to normal. This happens randomly either on the highway on cruising inner city 45-55 mph. Transmission temp seems okay, I have a gauge.
Truck does have a diablo sport programmer. Every since I got the truck, it came with the programmer, and shifts smooth with it. If you take the programmer out and turn it back to Stock Tune, the truck shifts hard.
I already had the cooler valve changed, and also the shift solenoid pack, but my Truck is STILL doing the same thing.
This just started happening last week.
I'm hoping somebody can give me an idea on what to change next?
Am I causing damage by continuing to use the truck in this state?
Should I keep it parked until fixed?

 

It sounds like your turbo is surging.

 

You will get better info in the power stroke section. This area deals with the old IDI 7.3, no electronics required.

 

Sounds like the torque converter locking/unlocking to me. My dodge did that (they have a problem with electrical noise and grounds). Fords don't have that problem, so if it's that it might be time for a relay (easy) or transmission work (not so easy).

Agreed on the powerstroke forum being a better choice, but the transmissions are electronic in the od trucks, even with the mechanical pumps.