Aw4 will not upshift intermittently

1989 xj 4.0l w/ cruise
It will not upshift automatically or manually. Gets stuck in 1st. It happens about once a day for the last week regardless of the temperature. Fuses are good, TPS is functioning and adjusted correctly. It runs and starts fine with or without shift symptoms. fluid is clean and regularly changed.
Any help?
Also, there is a resistor near the tcm fuse, shares power. Is it for the C/c? symptoms still exsist with or without this resistor plugged in
thanks!

If the inline VSS in the speedo cable was intermittent would it cause this problem too?

Get a good scanner seee if u have selnoid codes goodluck

I have fixed my problem a while back but did not report my cure, so here it is. Coolant contaminated trans fluid. I had previously replaced the radiator. the new trans cooler must have been defective. I didn't find out till I pulled the trans drain plug, the fluid was milky. luckily I live close to work and everything else I hardly drive my xj. So after the bad cooler to the new one I drove it maybe 200 miles. New radiator, trans filter, and 2 trans flushes she shifts properly. it has been about 250 miles since repairs. I couldn't tell on the dipstick, the fluid looked ok.