Hi, It could quite easily be the rotor arm faulty. As cylinder pressure rises the ignition system has a more difficult job to produce a spark at the plug. If the insulation of the rotor arm is at fault the spark from the coil can short to earth. To test the rotor arm remove the distributor cap, hold the coil lead with insulated pliers 10mm from centre of rotor arm & have someone crank the engine if there is a strong spark to the centre of the rotor arm it is faulty.
Regards Gary
Regards Gary
