New to forum and need some help with 99 tahoe 4x4 5.7 350

[elcaco37]

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

 

[elcaco37]

Really

Wow nothing

 

[LOWKEY]

pull the oil stick and check for milky like substance, same with radiator also. scanner wont tell you whats wrong besides what the computer says. compression test the cylinders after visual check on those fluids.