On the last couple of trips in the Bronco I've found that it won't hold a lower gear under hard acceleration or downshift when I put my foot to the floor. Rather, on acceleration it'll shift at about 3300 rpms (rather than running all the way up to the 4500 redline) and when cruising on the highway if I put my foot down to call for a downshift and get up a hill it won't downshift till the truck has really slowed down. If I disengaged the O/D using the button on the gearshift or drop the transmission into '2' I get an instant response and the truck drives as it should. Shifts are still reasonably quick, the fluid is at the right level and still nice and pink, and the transmission doesn't seem to be slipping. Driving around town and anytime I'm easy on the gas it seems fine. It's like the transmission is out of touch with the accelerator pedal or getting the wrong story from the computer.
Thoughts on what's causing this one?
It's a 1992 Fullsize Bronco, 351, E4OD, 202,000 miles (still the original tranny)