[DSG2003Mach1]

I would verify that connector to both the injector and coil pack are good - on my lightning one of the coil connectors broke so you could just slide it on and off. I'd go ahead and just trace out the visible wiring while you're at it for obvious rubs. Could be anything down to a bad coil or injector driver on the pcm even.

This is one of those things it might be worth ponying up to let a shop with the IDS computer hook up to it and see whats going on. They identified my misfire cause within a couple of minutes. $95 and a ziptie later I was on my way (i replaced the connectors myself when I got home). IDS can also identify low compression (relative to other cylinders, not an absolute number).