HARSH 1-2, 2-3, 3-4 OR 3-2 SHIFTS - Lockup Solenoid Malfunction. Remove valve body and replace solenoid assembly.
SHIFTS DELAYED OR ERRATIC (SHIFTS ALSO HARSH AT TIMES)
1. Fluid Level Low/High. 1. Correct fluid level and check for leaks if low.
2. Fluid Filter Clogged. 2. Replace filter. If filter and fluid contained clutch material or metal particles, an overhaul may be necessary. Perform lube flow test.
3. Throttle Linkage Misadjusted. 3. Adjust linkage as described in service section.
4. Throttle Linkage Binding. 4. Check cable for binding. Check for return to closed throttle at transmission.
5. Gearshift Linkage/Cable Misadjusted. 5. Adjust linkage/cable as described in service section.
6. Clutch or Servo Failure. 6. Remove valve body and air test clutch, and band servo operation. Disassemble and repair transmission as needed.
7. Governor Circuit Electrical Fault. 7. Test using DRB and repair as required.
8. Front Band Misadjusted. 8. Adjust band.
9. Pump Suction Passage Leak. 9. Check for excessive foam on dipstick after normal driving. Check for loose pump bolts, defective gasket. Replace
pump assembly if needed.
This is the approach I would take, mostly because i hate spending money on a vehicle.
You may be on the right track with your electrical suspicions. Disconnect battery, and clean PCM connectors as described in when you click the green link below (#1). Then clean the connector on top of the transmission.
I would check all cable adjustments. Pay particular attention to the throttle valve at the transmission. Adjustment doesnt mean anything if the lever is sticking.
If none of that works out, time to drop the pan and replace the solenoids and sensor if you dont see any signs of mechanical failure.
There are also some springs in the valve body that are easy to check/change at this point, but i cant help you there.