Volvo S70 Engine Problems cont.

After checking it out with an OBD-II code reader, I got 5 codes: 4 were for cylinders 1,2,4 and 5 misfiring, the fifth code was simply "multiple cylinders misfiring". First step towards a solution is replacing the distributor cap and the rotor. Ended up replacing the distributor cap and rotor, still wouldn&start. Replaced spark plugs and spark plug wires and she ran good as new This problem ended up coming back 20,000km later with an even worse misfire due to oil in the distributor cap. I determined the source of the oil was due to the PCV system being clogged, which was pushing oil out through the rear cam seal and into the rotor/distributor. So I replaced the PCV system, cam seal, and cap and rotor again to get it running perfectly.