Ford F-150 - 1997-2003 :: Misfire / Rough Idle With Sulfur Smell - White Exhaust?

My 2003 F150, 5.4L has been having some rough idle/misfires issues both at idle and under load.

I have fixed one big vacuum leak, replaced the PCV valve, new sparkplugs, seafoam and heet in the gas, replaced fuel filter, tested the fuel injector resistance. Coolant levels have not changed. The truck burns about a quart of oil every 1000 miles or so. The white exhaust is heavier than condensation, but it comes and goes. The rough idling comes and goes as well, and it usually happens under load and the CEL flashes.

The codes I get are random cylinders, po303, po308, po171, po174 were the most recent but there have been other cylinders as well. I clear the codes after each attempt to fix it and they come back different.

I notice that there is a small exhaust leak that drips water just behind the engine, and when I shut down the truck a lot of water will pour out of an area just behind the cab on the passenger side as well as out of the bottom of the muffler (small hole, looks drilled).

Usually the rough idle occurs after filling up the tank, but from different stations so I do not think it would be watery gas. I use Heet every fill up as well. Also, there is a sulfur smell after the rough idling occurs (catalytic converter?).