My 2005 4.8 automatic with 102,000 miles has developed a miss or "skip" whenever I'm lugging around trying to save fuel. Most noticeable around 1500 rpm's when I'm in OD and the torque converter is lockout out. Apply more pedal and it stops. We hooked a computer to it and it showed cylinder 2,3,4,5,6,&7 randomly misfiring. I'm thinking new plugs, not sure if they have ever been touched, might add wires while I'm at it. Any comments or suggestions? No engine light and no faults are shown.