Transmission is slipping any idead?

I have an 05 f150 4x4 4.6l and truck runs good it just wont
move forward. A family member bought this truck it has a
6 inch lift and 35 inch tires. When bought and driving
home it started to run tough after about half hour.
Scanned for codes got misfires so changed a couple plugs
and coils.  Took out driving again and the truck started
running worse , it could barely move forward. Pulled over
to shut off and restart upon restart truck wouldn't go
forward  only backwards. So backed in to a gas station
and towed to my house. I scanned and got p0720 and
p2106 codes. So I changed output speed sensor to both
transmission and transfer case. Changed fluid and filter
and got the truck to drive again. But after a while of
driving it started running rough again and went into limp
mode again. Got it back home scanned again same codes
came up.  Now I went and replaced the output speed
sensor and filter and fluid again. Put truck in drive it
engages but barely . Gets to 3000 rpms and trans fault
comes back on and limp mode. Put in 4 low put in drive
can get to move forward more before trans fault.
Meanwhile in between all this I keep clearing codes . I just
would like some input as to what else I should try before
replacing tranny. Any help would be appreciated.  Thanks