Code P300

I replaced the engine 9 years ago with Jasper engine. The timing belt broke 2 months ago. When I pulled #1 spark plug it had oil all over the spark plug boot. It came in this time with running problem. It had multiple codes. I cleared them, first code came back P300 and engine light is flashing within a minute. I cleared it, let it run longer and second code came in P0335. I replaced crank sensor. Cleared codes and under a minute engine light blinking and P300 again. Then on the thinking, oil may have ground out the spark plug, I replaced valve cover gasket and spark plugs. Cleared codes started it again same P300 code and blinking check engine light. Saw on the scanner cylinder misfire on cylinder 2 and 3. By their location, I thought bad coil pack. Replaced the coil pack, still misfiring on 2 and 3. I performed a compression test 3 were at 160 and 1 was at 150. Looked at old coil pack, noticed cracks in the plastic seal under the pack. Cylinder 3 spark plug lead was tarnished, the other 3 were gold. My question is, could it have sparked the computer and cause the P300?