I'm having a problem with my 96 2.5 engine I have never seen like this before. It has 186k, in good shape. This is intermittent and runs fine otherwise.It sometimes on accelleration, has a severe stumble that clears up with a muffled backfire in the air cleaner box sometimes, along with a check engine light usually and a poor idle. The code is 27.I have checked everything and am now looking at the injectors/fuel pressure.I also am now(all the time!)getting a really bad ignition noise except on a local station ,on the FM stations and when idling outside and the TV is on, a oscilloscope type bar running up the tv screen!I have checked all engine grounds and the plugs look ok as well as the plug wires/ dist seem to be okay.It runs great otherwise so it is a mystery to me! This is my 5th Cherokee and I've never come across this so any help would be appreciated. It does have a little exhaust man.leak and I would say the timing chain has a little noise too, and the oil in the air cleaner box, but otherwise okay.