Since the tranny has been in, when I'm driving in OD, at 2,000 RPM, and I let off the gas a little bit,to slow down. It will slip into 3rd gear then I have to rev the motor back up to get it to shift back into OD. My VSS doesn't work, Code 24 plus speedo doesn't work. My scanner says my TCC isn't locking up in any gear. When I'm trying to cruise at 2,000 RPM on the highway, the scanner says I keep going back and forward from 3rd to 4th, but it feels like it's still in one gear. Also the scanner says my park/neutral switch doesn't engage. I can't start it in Neutral, only Park.

Guesses, from all the entries I read on here, came up with these: VSS, brake pedal switch, idle stop solenoid, and park/neutral switch.

Any other guesses?

87 GTA, 700R4 B4C package, 3.73 gears, 355 TPI, no A/C or emissions.

Also it idles at 1,000 RPM in Park and Neutral and drops down to 450-500 RPM in other gears.