Ya their are a couple of things the tcm uses to calculate shift. One is the tp (throttle position) senser you should see .5 volts closed throttle and close to 5 v wide open throttle. If this is mest up your tcm thinks you are just half assing the pedal.

The next is the ect (engine coolant temp senser) with a hot engine you will see close to 5 volts and with a cold engine close to 0 volts. A cold engine will not shift on red line.(your engine may be hot the tcm will not know this)

Their is also some upshift/downshift comparative signals used to communicate between the ecm and tcm. Also a shift acknowledgment communication line between the 2 any of this will mes with your shift.

I wish you had a d4 light we probably have a tcm dtc.

I will try again if you are ready. Private message me and be prepared to make your volt meter your best friend.