No coil tests that I could find.

But your car has individual coil packs, correct? If a coil was the problem, you would (probably) get a 301 to 306 for the particular cylinder.

I would take a close look at the wiring harness' insulation, although this was supposed to be fixed by '97. I would check carefully for vacuum leaks. And see what the oxygen sensors' and adaption readings were saying.

Beyond that you would need the full diagnostic system to pinpoint the problem.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe