Re: Maybe Someone Can Help
This is a tough one but I'll take a shot. I'm guessing it's not a fuel problem but it can't be completely ruled out. It sounds to me like you're dropping a cylinder and the problem could be temperature related. With that thought it's going to be tough to find the cause without going through a guess and replace process. Because it comes and goes at full throttle I can guess that a plug is fouling due to poor spark. It's impossible to tell which one because when you back off it comes back so shutting down and pulling the plugs would probably not show anything. You could test the coils but they will probably test good also. However, heat can cause a coil winding to separate and stop functioning at full capacity which would cause your symptom. The problem you have is which coil is it? It probably isn't the trigger coil because that would effect all cylinders and there would be a huge loss of power. I suspect it's one of the four ignition coils. I'm afraid my theory is going to require an easter egg hunt but this is where I would start. Buy one new coil (they are all the same) and replace and old one, one at a time. If you get lucky, you'll hit it on the first shot. If not you're only out the cost of a single coil and changing them is relatively easy.
