Trying to cross ditch, got stuck. Tried to put in 4wd and wouldn't engage. I then started to rock truck back and forth to get unstuck. After several minutes of giving it gas in forward and reverse and spinning on grass, finally got unstuck. After this, truck ran but had no power. Had to pretty much floor it to get it to go. Had sorta knocking sound in engine and at stop light or stop sign would stall if gas was not applied while holding break. When it would stall, the tuck could be jump started with cables and it would run the same way. Is the engine gone? What could it b? Thanks!