92 Auto Transmission problems...

i think the problem is that it doesnt upshift, the engine revs and revs for ever, untill i stop, and it decelerates reallllly fast. It seems as if its stuck in 1st, but sometimes 2nd gear. i can drive in 3, low, and drive, but something is wrong. need to know what changes the gear, ie vaccum, cable, or computer. NEED HELP ASAP! thanks