So my 6.4 seems like it has completely lost its power. Keep in mind it is stock no tune exhaust or anything. From a dead stop it accelerates fine up until about 45 mph and some times it shifts hard out of what I'm think is 3 or 4th gear and sometimes it will rev up to about 2500 rpm and the speed and rpm just stalls. I have to let of the gas and ease back on it for it to go faster. The other day I was getting on the highway and the pedal to the floor and my speed was just slowly rising. I've had some people tell me the torque converter, clutch is slipping, or the exhaust filter is backed up. Can anybody help me out?