1976 Spider, stock, SPICA, Marelli points distributer and coil, is reluctant to run on four cylinders. Starts and runs, chugging on one or two. High tension leads show dead or intermitent spark on two or more cylinders at any given time using timing light. Installed new battery, points, rotor, condenser, cap and high tension leads with no improvement. Have tried two sets of spark plugs, NGK and Golden Lodge, to no effect. Points are set at .017, dwell of 60, ignition, valve, and injection timing are all correct. Wiring appears correct per wiring diagram. Substituted a test coil in place of the Marelli with no change. Ordered a Bosch Blue, not yet arrived. Spark is not as hot and blue as I would anticipate. New to Alfa's having mostly worked on British cars. Anyone have any ideas or similar experiences? I've studied the threads and found a lot of collective wisdom and experience, but didn't find a situation quite like this. Any input would be appreciated. Thanks.