1st things 1st. As mentioned above check your cac boots for tears or loose fit, maybe even 1 coming off. 2nd, I would do a complete service on the truck since you do not have the maint. history. Change all the filters, the oil, coolant and have the trans. flushed. You need to start with a known base of operation. A plugged fuel filter could also be a culprit and if that is the case it can be very hard on your injectors.
