Calling all engine guru\'s Getting ready for a two week camping trip. So even though everything was running ok I decided to give the Jimmy a tune up. I changed the plugs(ac delco cr 43st) the wires(msd helicore) and the cap and rotor(stock autozone replacements). After the truck runs rough around 35-45 mph. I checked the wires (all 2k-3k ohms) and made sure all had good conections. Also changed the o2 sensor during tuneup. So put the original back in after checks and test drove it. Seemed better but still some hesitation (seems kind of like missing) at 35-45. Could it be a vacume problem /forums/images/icons/confused.gif I noticed that the previouse owner had ac delco 44T plugs in. They are a little shorter after the threads. (the center electrode doesn't protrude as far out as the 43st's.) Could that make a difference? I was wondering what those of you with ac delco plugs are using? Going to drive it to work tomorrow (66 round trip) and see how it goes.