Jeep: Shifting Problem with Jeep GC Please help!!! TIA

Have a 1998 Jeep GC 4.0L that's having trouble making it's first
shift. The rpm's run up to over3000 while the speed hangs at 25mph.
Sometimes backing off the gas allows it to shift most of the time I
have to drop into netural then back to drive to get it to shift.
I've changed the transmission fluid & filter(fluid still red, not
black) tried resetting the computer and changed the throttle senser.

What else might help before going to the shop for the usual
LARGE bill???