2003 Silhouette won't go

I have a 2003 olds silhouette. This problem just started today and I have no other known problems with van. I was at a stop and when I gave it the gas It wouldn't go. Then engines was revving and it was in gear but wouldn't go. When I turned it off an resterted it would go but when I would slow as to turn a corner and tried to give it gas it wouldn't go again unless I turned off and restarted. It will only go for a few minutes and if I slow down it won't go to speed up again. Thank You.