Originally Posted by woodysand

OK guys, I found the trouble and I am embarrassed to tell you, although in my defense when I bought the truck back in August it was already like this and the previous owner said he had the exact same problem since he got the truck from his father-in-laws estate. The father-in-law was the first owner . I wanted to check the compression one more time before I pulled the heads. The compression was 140-147 with the throttle plate closed so the real compression was higher. That is ok, not new but ok. Something in my mind made me look up the firing order and use that instead of putting the wires back where they came off. Here is the embarrassing part. After several hundred dollars in parts and scores of hours of my spare time, I found 4 and 6 sparkplug wires were reversed. I couldn't believe the engine ran as good as it did at low speed with the wires crossed but when they were wired up right, the truck went right up to 75 mph. I caught up with traffic at that point and turned around and went back home. How could a motor run well like that at slower speed with 2 wires crossed. I read a thread from about ten years ago that the problem sounded just like mine. A bunch of the same suggestions were tried and that guy sounded as frustrated as I was but he just abandoned the thread and disappeared off the site without a resolution. I figure he either never solved his problem and sold the truck, or he completely rebuilt the motor and got the wires right when he put it together or he found what I did and was too embarrassed to admit it and quietly disappeared. If he had fessed up and finished the thread it would of saved me a bunch of time and money. Anyone ever seen anything like this before?