Had the fuel filter changed recently, the plugs are fouling out,can't figure it out. Getting a 61 code even after disconnecting the battery for awhile. Great air filter, good gas, new plugs. Only 800 hrs, I know it was suppost to go 1500 hrs on that Bosch filter. Isn't there a sensor that moves the engine out of closed loop after it warms up ? Maybe the injectors are clogged . Always ran 89 gas. Starts good and runs until the plugs foul. Could it be electrical ? The dealer is an hour away thought I'd ask questions first.