1994 dodge ram 2500 v8 5.9

Hey Eric and guys I have a huge problem with my dodge. It started acting very weak when I went to work in the morning when I was on the highway. It started acting weak slowly. But then it got to the point of having to floor it only doing 40-45 mph just to get off the highway and get towed. I really dont know why. When I got home it would start but if i floored it, it would only rev to 2500 or 3000 max. PLEASE HELP.