Just started doing this today. Rough when restarted warm, tends to smooth out, but not entirely. Pulled the plug wires off individually; 1 and 2 the same, 3 easily arced a good distance and all made the engine stumble when disconnected, 4 had almost no change and almost didn't arc at all. Hooked up a scan tool to the engine, and the timing swung in a wide range of 5-6 degrees. Usually it only swings 1-2 degrees, if that. Am I looking at coil packs, plug wires, plugs, camshaft sensor, what? Any way to narrow down what I really need?

bump, just this once. Already did a search, came up nothing relavant. Still need some help.