99 Jeep Automatic Transmission failure

Three related problems have occured recently with my 99 Jeep Grand Cherokee automatic transmission (4.0 liter eng, 96k miles). Here’s what I am experiencing:

1. When eng/trans cold and warming up, noticeable rumbling (shuddering) when acccerating from stop, but not with automatic shift into higher gears.

2. Transmission hangs up in high gear when decelerating after 10-20 minutes of sustained 60+ mph highway driving. First noticed when accelerating after a stop on off ramp - low gear not engaged, acceleration slow. Though car does not buck, the acceleration is very slow -like trying to accelerate in 3rd or 4th gear with a manual transmission from a stop Unnerving in traffic! This is a recurring problem. Transmission can be shifted manually and seems to function normally. Overdrive seems to work.

3. Whining/rubbing noise that increases with speed: maintains constant pitch when at speed, goes away when decelerating or stopped.

Checked fluid (low but not empty), but problems did not change with addition of fluid. No evidence of external fluid leak on frame, undercarriage or parking spot; suspect internal leaking. I have taken it to the shop and am awaiting the report.

Have you ever had the transmission serviced before? There is a maintenance interval specified in the owner’s manual for the transmission. I believe (for this transmission) you are supposed to have it serviced every 30K miles. Did you check the fluid level with the transmission warmed up, on a level surface and with it in neutral?

Whatever you do, don’t let the shop put anything but ATF+4 in the transmission. It is the required fluid. Anything else will eventually cause problems beyond what you already have. But, it sounds like you need to have some work done on it.