I have an 07 Avalanche with 240k miles that developed a cylinder 1 misfire several months ago. My mechanic and I have changed spark plugs and wires, swapped coils, replaced the intake manifold, swapped injectors, checked compression and leak down, pulled the valve cover and confirmed the cam lift. Some of these things we did more than once just to be sure.

Strangely enough, my wife's Suburban developed a cylinder 2 misfire around the same time, although intermittent, and I can't figure that one out either. This makes me think it's a common problem, but I can't find anything else in any posts that would affect only one cylinder.

Any suggestions on what I can do next? I'm at a loss.