I pulled the distributor and lined up the #1 wire with the alignment notch and then checked the timing. The timing is perfect at 5 degrees ATDC, but runs a little rougher. Whoever had the car before me had the timing advanced a bit to raise the RPMs to smooth out the 4 missing cylinders.

AT higher RPMs the missing smoothes out a bit, but I believe the 4 missing cylinders are still missing.

I wish I knew for certain if the ECU is working because I do not want to spend that kind of money on a guess, but if it is not the ECU I have no idea where to look from here. I believe I have eliminated all other possibilites. -Mike

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1973 280SEL 4.5