99 F150 4.2 low rpm miss MAF sensor cleaned new fuel filter new plugs and wires.still has a miss when I feather the gas pedal in traffic or on the highway and barely giving it gas. Unpluged the EGR plugged both lines to keep vacume problem gone.Will I hurt anything keeping it unplugged like it is now? We don't have emission test here. thanks DON

 

The Egr System Uses Exhaust Gases, Which Are Cooler Than The Combustion Flame To Reduce Combustion Chamber Temperatures, Thereby Reducing Nox Emissions. Leaving The Egr Valve Vacuum Lines Disconnected Will Cause The Combustion Chamber Temperatures To Rise, Creating A Greater Chance For Spark Knock (pinging), Which Will Affect The Performance And Efficiency Of The Engine In A Negative Manner (lower Power And Economy). The Best And Most Economical Thing For You To Do Is To Repair The System To Restore Proper Operation. Good Luck, Dan.