Yesterday I was working on adding an external regulator and may have created another problem. Today the transmission won't shift out of third gear. It starts off in third. and once you get going it won't upshift to overdrive nor will the t/c lockup.

While I was working on it yesterday I removed the connectors from the pcm to check for corrosion. That's the only thing I can think off that I messed with that might have anything at all to do with the tranny. Does anyone have any ideas?

 

You probably messed up a connector at the pcm if that's the only thing you messed with. I had to deal with almost the same thing recently on a friend's truck. Had to take the pcm connector apart and squeeze the female connectors so they fit tighter. Too much di-electric grease on the PCM connectors can also cause problems if it allows the low voltage signals to jump from pin to pin.