I’ve been having an intermittent issue while towing my 15k fifth wheel cross country the past couple days. It’s hard to explain so please bear with me. My truck is a 2017 F350 SRW with 38k on it.

At highway speeds, the truck will surge very slightly while accelerating and decelerating to maintain speed. The surging will go away entirely when the truck needs to downshift or put more power out to maintain speed. Same when using the engine brake and gearing to maintain speed down hill.

Today, while accelerating from a light, it went through 1st, 2nd, and 3rd just fine. When the torque converter locked in 3rd the surging started and got violent to the point of my dash cam falling off the windshield and I had to let off the throttle entirely.

The surging is almost like the engine is loosing all power, and then giving it all back, every 100 rpm. It also continues to get worse if you don’t let off the throttle.

I used for scan when we disconnected from the trailer and there were no DTCs for any modules and the truck drives perfect unloaded.

Any ideas on why? It seems related to when the TC locks and it’s the most aggressive in 3rd when accelerating after lockup, but it happens the a lesser degree in 4, 5, and 6. We just got into Nebraska from California tonight and have another 4-5k miles towing to do. I’d really like to have it run correctly.