boertje

3 days ago I was coming to a traffic light and had to slow to 30mph. As traffic was picking back up I noticed my auto tranny not shifting down. It was stuck in 4th. Didn't think too much about it until I came to the next light where I had to stop. When it came my turn to go and took my foot from the brake to accelerate my engine died because again it was stuck in 4th since it had not downshifted. I restarted the engine but the shifting was weird. It wouldn't shift from first to 2nd until 2200 RPM and as soon as it did the check engine light came on. I was having an intermittent check engine light problem anyway that was low map voltage and so some days prior to all this I removed my Banks stinger plus and restored my turbo to factory (actually the power was still quite adequate).
I just recently replace the throttle assembly and my engine is completely stock again and now this new problem shows up.
After I reconnect my batteries from a 20 minute disconnect and the check engine light is out, I start the engine and I can rev it up and down all day long with no light, but put it in drive and as soon as I shift from 1 to 2 the check engine light is on again and the shift occurs at 2200 RPM. Some 120,000 miles ago I had installed a BD torque converter and valve body and some other pressure enhancing goodies. These have worked great all these years.
Does anyone have any ideas?

boertje

Tranny speed sensor on the blink. Replaced and all is well.