Electrical problem with 1978 Wagoneer. 360 4-barrel. Ignition electrical problem. I have 12V power going to the coil and the coil is tested as good. ECM was tested as good but I am not getting spark at the spark plug. Replaced rotor and pickup in distributor. Jeep cranks over and just went out randomly. Prior to this, vehicle ran then I only got spark when cranking over the engine. Now, crank only but no spark at plugs. Any ideas would be appreciated.