So last year I did the wires on the truck as one pulled apart, ended up having to buy whole new set, anyway did spark plugs recently and one wire broke again, so had to buy a new set, but as the others are not that old I just replaced the broken one. Fired it up before I reconnected the air cleaner, and the maff I think they call it was not hooked up so got a code right away, so put it all back together and cleared code, did fuel filter also as I had not done it when I changed my fuel pump a year or so ago. Anyway now in the last little while truck will stumble while sitting or driving and nothing seems to be out of sorts, no codes. I was told because I buy my gas at Costco that could be it, but I put in fuel injector cleaner and that should keep it clean. One thing I thought was maybe that fuel press regulator inside the upper manifold, but a mechanic told me I would smell gas if that was not good. So any ideas on where to start looking for problems? Cap and rotor were done at least two years ago I recall.