[spudz]

your truck has 4 o2 sensors, 2 before the cats, and 2 after. you said the left bank was misfiring. Most likely the cat on that side is clogged. And if you remove the cats, the truck will run fine but you will have a check engine light on unless you get the rear 02 sensors programmed out by a tuner. I dont think anything was ever wrong with the MAF. Put it this way, it can only suck in as much air as it can put out. So if the exit is clogged, it wont be able to get as much air in the front. The computer sees that its not flowing the right amount of air and throws a MAF code.