99 tahoe 1500 4x4 350 5.7L 155000 miles 4l60e.Ok I was heading home from the lake a few weeks back and I was pulling 2 jet skis up a hill in 3rd gas peddle half way at 3500 rpm and 50 mph. And my tahoe made a pop under the hood. Backfire maybe. Then it started running rough right when it popped. So I put a hole dist in it and a crank sensor and still just runs like crap. It makes a air hissing sound under the hood. ran a scanner on it and it says cats are bad but it punched a hole in then just so see if that's it and it's not. now order New ones but want it to run right first. I just trying to see what you think I should do next. I was thinking fuel injection or timing chain? Truck seems like its off time