ok i just got done replacing the head gaskets on my car and now when i start it up it runs like $hit. I have the timing at 14 deg, and when its trying to idle its like it backfires into the valve covers. If you give it some gas to keep it running it will sputter a little and a dull fffooompp will come from inside the driver side valve cover. Ive never seen this before do you guys have any ideas??? thanks alot!