It does sound like missfire on one pot. I have a similar situation. I had a blocked breather which led to blown cam gaskets, so oil in plug wells. I fixed it all last weekend, however I maybe didn't dry out the coil packs fully, and sometimes on LPG ( which puts a higher load on the sparking system) it missfires, Sometimes I can hear the slight tick of a spark going direct to the block. If I drive reasonably and avoid planting the right foot, its fine, however once I did accelerate fully, I got missfire, the ECU shut down one cylinder, and a 6 pot engine running on 5 shakes a lot, and put on the lambda light. I got over to the hard shoulder turned off and back on, car now running on all 6. I am waiting for a warm, dry day to clean the coil packs out properly.
It is possible that your problems are caused by something else, (poss breathers blocked ? ), which can lead to a sparking problem. If you get the shaking again, see if a restart cures it. Taking the scuttle off is actually very easy; I was a bit apprehensive initially, but a few clips, wipers, one screw and its off, and it makes seeing things so much easier. It makes doing the breathers very easy, esp if you use my sons air pressure method !.
Best of luck,
Ken