My truck seems to change in and out of high and low it will die or chug as if the fuel was cut off it starts back but when idling it chugs now here is the tricky part it don't do it everyday just 1-2 days a week or when it is raining I ve tried catalytic converter new plugs wires injector cleaners this truck is a350 auto with plenty of power but it seems to be a mystery problem around here any help