Engine problems need help!!

[GodStang]

I have a 1994 Mustang V6. It has 105,000 miles. I have put a K&N air filter, new wires, and new spark plugs. new head gaskets and machined the heads.
Now with my problem. When I drive the engine will miss fire BAD. The whole car will jerk really really hard. It feels like you are letting the cluth out two early. But the cluth is not even being touched. Some times it does it once in a blue moon, sometimes it will do it 50 to 60 times in a row. Also one day I had my car on and lights and radio. I was talking to a friend letting it idle all the lights shut off the clock and radio went out and the car turned offand than came back on and ran normal. The check engine lite comes on and when it misses sometimes it will go off. I have takin it to get looked at and the codes could not be read. Any help would be appricated.

Josh Godbee