No Forward Or Reverse gears

I have a 93 grandprix LE with a 3.1l and an automatic transmission. My wife was driving it when it just stopped accelerating, engine would rev but wouldnt continue to go she said it didnt make any noise when it happened. when i put it in gear either reverse or drive it just acts like it is in nuetral no engine hesitation like the transimission just isnt there. it was acting up a little prior to this like it was not wanting to downshift when going up hills it would just bog down. i checked the transmision fluid it looks good no discoloration but it appears to be over serviced like the transmission isnt moving the fluid around because i now it was good 2 days ago when i got gas it was good. and now i am noticing a clunking sound coming from the drivers side of the engine but below it because the engine itself sounds fine? any ideas wat the problem could be?

I would definitly take it to a qualified transmission tech and see what he says. Sounds like it isn't good.