I have a 97 chevy with a 5.7L that seems to lose power on the highway. I have changed all the usual stuff. plugs, wires, and the cap and rotor. I changed the oil also. It seems that this truck would haul ass but it wants to down shift while passig all the time and seems to struggle at highway speeds. I would like it to run like a champ when I haul my boat any suggestions would be awesome!