Smells like gas and white smoke...You are running rich. That rules out anything to do with knock sensors, starter and flexplate. Flashing check engine light is a warning of active detonation (spark preignition/ aka spark knock). 2 things I would look for while troubleshooting this. The easy one is first. Look for missing spark. Id check the spark plug wire and its coil at #7 which is the one you said was fouled. Turn the lights out (GO outside at night) and raise hood and start engine. See if you see any flashes of light around spark plug wires and ignition coils. Listen for a snapping noise which may also sound alot like a tick. A cracked igniton coil or bad spark plug wire (cracked, broken off) will cause the symptom you have. Second thing to check is the Bank 1 and 2 Pre cat O2 sensors. Compare them and see if they are similar in value AND switching values. They will immediately start showing readings once engine is started. Their values are ignored until engine is in closed loop. Third is a bad fuel injector or its associated wiring. It would be sticking open intermittently or possibly all the time. Check your oil dipstick for smell of gas in your oil. Change oil if you smell gas in it!
