Plugs #1,3 and 2,4 fouling

dodgetkboy love your engine pics,I'm leaning towards restrictive breather/choke,carb looked to be fine,I use it as a daily driver year round(northern Alberta)combined driving,was a 508 purple,changed to a stock 340 lift purple(truck weighs 4200lbs and I got tired of revving the crap out of it)this has happened twice in last couple months,I've changed gas stations and same thing.