I'm not an expert, but it sounds like either you're getting no spark or air in Cyl #4. How many cylinders do you have? If you have 8, maybe you're running on 7 without knowing. Depending on your car, it may be possible to see whether the spark plugs work by putting the ground electrode on your engine head while someone cranks the ignition a few turns. If you are getting spark, then you're probably not getting any air.

Btw, by gas fouling, are you talking about wet, clear fuel? Or are are you talking about a form of carbon fouling--wet or dry black soot? If it's carbon fouling, then none of what I said above applies....