My 1988 240GL, 120K, began starting and running as if one cylinder was missing. I installed new plugs, high tension wires, dist. cap and rotor, and a different air mass meter. It got better, but... Yesterday during state emission check, which requires checking tailpipe emissions 90 seconds at idle and 90 seconds at 2500 rpm, it still was missing on sort of a random basis, obvious even at 2500. (BTW it passed the test, to surprise of the test guy) Now I'm deciding what to do next besides throwing in the towel and taking it to my Volvo tech ($70 per hour). I think it must be the fuel system somewhere, your suggestions will be greatly appreciated. Bob