Thanks, guys! But the timing light is a plain-jane lamp with no adjustments, and the balancer is a one-piece unit. I still believe that the computer is not sensing the engine position. It did start today with some difficulty, and ran pretty smooth except at idle. May take a video of the timing mark ...

Have been troubleshooting my 1988 740 8 valve fuel injected wagon for about a year. Mostly just hard starting, but last couple months running rough at idle and REALLY hard starting. Have replaced: fuel pump and filter, ignition module, distributor, cap, rotor, plugs and plug wires. Coil tests good. ...