Maybe im reading to much into this but just before mine started to run real rough on idle i could smell petrol, I put that down to a small bird in my air box (not nice sight!) restricting the air flow, now it runs like sh!te on idle but still ok when your off and driving. I thought it was the EGR valve (still not fixed) or maybe the coil pack.
A compression test will sometimes give inaccurate readings, if it holds compression once then its normally fine, bloody modern cars with senors!