[iccmiller]

Shuttle Shift is what you are experiencing.

Do a search for shuttle shift and you will find out that you need to replace the governer pressure sensor and transducer. There are lots of write ups on here about how to do it.

It is very easy to do. If you can change your transmission fluid and filter you can change these.

FWIW, the 47RE and 48RE are 3 speed transmissions. What feels like 4th is when the torque converter locks up around 43 MPH.

 

[5.9x2]

I thought our transmissions were 4 speeds. 3 speed 727 with an O/D bolted on the back making forth and then also a Lock-up on the TC

 

[gravyd]

4 speeds plus tcc (lockup)

 

[DRCMILLER]

Ok, I have a similar problem then on my 2003 5.9 Auto 4x2. Shift 1 through 3 OK but not into 4 or OD. When I manually put it in 2nd it won't downshift from 3 to 2 unless I step on the fuel. Can shift manually from 2 to 1 OK. Cruise doesn't work. Two Dealers in town and they are only guessing - they have both said they need to start with TPS. Error code was P0123. I'm lost on this as are the Dealers.
DRCMILLER