1996 Chevy Lumina tranny

My lumina has less than 80k. It shifts gears up @ 1200 rpm, and doesnt downshift till like 500 rpm. I was told by a shady mechanic that I need a new transmission. But I have put well over 5000 miles on it and still runs the same. It runs ok briefly every so often. Another gentelman told that there is a electronic shift module that could have burnt out. To me it seems like an electric problem, but I dont know enough about it to say one way or another. Is there any electronic parts on my tranny, or do I need a new one?