Before you spend a lot of money, there are a couple of things you can test - the 2 pigtail components mounted to the coil bracket.... the rectangular one is an LC filter with 2 wires and the cylindrical one is a capacitor:

1) disconnect the capacitor lead, touch the connector terminal to ground to bleed any charge.... now read resistance from the connector to engine ground - it should be infinite (no continuity).

2) disconnect both leads from the LC filter and ground them briefly. read resistance from both leads to ground (individually). Both should read infinite (no continuity). Now read across both leads - there should be SOME continuity (don't know how much), but a capacitor and resistor are inside the filter and the resistor bridges the 2 leads internally.

If either component's capacitor is shorted, they will bleed coil voltage to ground.

Other possibilities are the distributor and ignition wiring, but try those tests first.

Frank