Reverse issue

Hello
My truck after off-roading and some mudding
Has started acting weird when in Drive gear it moves flawlessly
But when in reverse the truck shakes (the rear tires and differential not the rest of the truck) and needs extra gas to move
Also when changing from neutral to reverse the engine idles up
Tranny fluid was changed around 4000 Miles ago
Truck is
2013 4x4 5.7 Rcsb

 

Define off roading and mudding. Did you have to rock out of a pit? Use 4wd? Bottom out? Catch brush? Catch a rock on one side?

 

No didn't hit anything underbody
I got stuck in mud the rear diff was stuck tight in mud
Had to get towed as my truck didn't have any traction in the mud
Yes i was using 4wd

 

Update
3rd 5th gear don’t shift at all
the transmission skips 3rd gear and shifts to 4th gear and skips 5th gear and shifts to 6th gear
Reverse now needs a lot of gas to move
I previously changed the SLT solenoid

 

No bueno.

Stop driving it. Get it tilt bedded to a shop.

 

Did you fix it?