Pulled these from my factory manual:
SLIPS IN FORWARD
DRIVE RANGES
1. Fluid Level Low. 1. Add fluid and check for leaks.
2. Fluid Foaming. 2. Check for high oil level, bad pump
gasket or seals, dirt between pump halves
and loose pump bolts. Replace pump if
necessary.
3. Throttle Linkage Mis-adjusted. 3. Adjust linkage.
4. Gearshift Linkage Mis-adjusted. 4. Adjust linkage.
5. Rear Clutch Worn. 5. Inspect and replace as needed.
6. Low Hydraulic Pressure Due to
Worn Pump, Incorrect Control
Pressure Adjustments, Valve Body
Warpage or Malfunction, Sticking,
Leaking Seal Rings, Clutch Seals
Leaking, Servo Leaks, Clogged Filter
or Cooler Lines.
6. Perform hydraulic and air pressure tests
to determine cause.
7. Rear Clutch Malfunction, Leaking
Seals or Worn Plates.
7. Air pressure check clutch-servo operation
and repair as required.
8. Overrunning Clutch Worn, Not
Holding (Slips in 1 Only).
8. Replace Clutch.
SLIPS IN LOW GEAR 9D9
ONLY, BUT NOT IN
MANUAL 1 POSITION
Overrunning Clutch Faulty. Replace overrunning clutch
If you have a way of testing the hydraulics, let me know I have the test procedures, or you can fine them in the service manual elsewhere in the 2nd gen section.
When you performaed the service on the filter, did you clean the check valve and flush the cooler? These plug real easy and can cause lots of porblems.
