Why does my car die as soon as i put it into gear?

I have a 91' Oldsmobile Cutlass Cierra and it'll start fine and idle fine in park and neutral, but as soon as i put it into reverse or drive it dies. It is has an automatic transmission. It's fuel injected. It has a V6 engine. It was running fine yesterday but today i drove around for about 20 mins. and when i came to park it, it died just as i pulled in and while i was driving whenever i took my foot off the accellerator it would start to sputter/shake a little bit and would sound like it was about to die and then as soon as i pressed the accelerator again it would be fine. so i started my car back up so i could park properly and then as soon as i put it into gear it died again. I tried to let it sit in park for a couple minutes and it was idling fine but when i put it in gear it died, i also tried reverse and it died as soon as i put it in gear there too. So if anyone can tell me what's wrong or what could be wrong that would help because i don't want to take it to a shop if it's something easy.