brake light, no shifting, no speedometer 93 Chevy Cheyenne 1500

A few weeks ago my trucks brake light came on, speedometer quit working and it wouldnt shift out of first. All at the same time. It done this once then everything started working five minutes later. This happened five, six times. Well now its stuck that way. I cant go very far in first gear. LoL I took it in and no codes came back. A friendly mechanic said it was the speed sensor. Replaced that to no avail. I went and bought a computer for it and put it in today and it made it miss and didnt solve the problem, so the old computer went back in. Does anyone have any ideas? Please let me know.