91 Talon AWD Turbo, Auto, won't shift down

It goes in reverse and neu., but even if you pull it down to low it still takes off in drive. Hammer it at speed and it won't kick down.
Took it to a local tranny guy and he couldn't find problem, all fuses and elec. looked good. He didn't want to start throughing exspensive computer parts at it.

Find a used TCU on www.dsmtrader.com . You are MOST LIKELY in limp mode. Pull the TCU from back behind the radio (mounted to the floorboard/firewall...NOT the ECU) and see if it smells like fish as a preliminary test.