1995 Dodge Avenger Low Gear Only (intermitant)

Sometimes I start the car and drive and the trans will not shift out of low.
I can move the gear selector to 2, low, or drive and the gear does not change.
RPMs soar of coarse.
Nuetral will take it out of gear.
I found I have to pull over, turn off the car, wait a few seconds and turn it back on. Shifts fine!
Sounds electronic or electrical or computer but not mechanical like linkage or link cable.
Please help!