1991 190E 2.6 spark failure

[just-n-time]

Hello every one, I have situation that is giving me some trouble. It is spark related, if this was an early chevy I would say bad ballast resister. symptoms are spark at first turn over of the engine, I have checked each and every plug wire threw my plug tester each one sparks once only when cranking the engine.
I have replace the cps at the rear of eng. I have changed the distributor cap cleaned the rotor and still no change, am I looking at coil or ezl?