After some repair work, my truck is running rough at times. High gear (OD) 55 mph or so, 1500 rpms, light throttle to accelerate, it feels like the engine wants to jump out from under the hood. Downshift, 2500 rpms, it is smooth as silk. I had the intake off, to replace the heater pipe underneath. When putting back together, I noticed the supply vacuum line to the EVR was broken. I repaired it, and my assistant insstalled the vac lines, fuel lines, etc. It was almost imposssible to see what you are doing, and I suspect my helper may not have put things back together correctly. The truck runs good in general, plenty power upon taking off from a light, etc, only when in high gear, low rpm, light throttle situation. I have tried to look at the vac connections, and it is impossible to see. Mirrors, lights, all to no avail. This weekend, I will try to perform a vac test on the lines, or else take parts back off to be able to see the EVR vac connections. Any other ideas are appreciated.
First I would suggest COPs. I am having the same problem right now, and mine has no compression in cylinder #5. Looking like it is valve and/or spring issue but again we are still working on mine. Hopefully you have the better luck than I have.