Several days ago, my normally great running '97 Expy 4WD 5.4 started to miss and stutter on acceleration. Having experienced bad coils in the past, I put my code reader on and it said cyl.#2 was misfiring, so I changed out the coil. It seemed to run better, but not perfect. Also, replaced the fuel canister purge hose because it had a small split. Next morning, I drove to town and it was running like crap. I ran the code reader again and came up with (Cyl.#2 Misfire), P0304(Cyl.#4 Misfire), and P0171(Bank 1 Too Lean). I also noticed a very minor noise from the right rear catalytic converter that sounded like an exhaust leak or baffle rattling. Next morning, when I started it, I crawled under and it was blowing visible exhaust (35 degrees outside temperature) from the cat. Here's my question: Can the hole in the cat cause such a large reduction in the operation of the engine and cause the error codes listed?? Thanks all!!