2002 Ford Expedition Possible EGR system failure.

Approximately eight months ago I took the vehicle in to have the spark plugs and COPs replaced due to some hesitation and misfiring. The problem persisted after dropping a few hundred dollars to fix what the mechanic deemed a common problem with Expeditions, and was told by this so-called reputable mechanic to take the truck somewhere else. The problem has begun to get worse as of late so I began to surf the web for advice or answers.

Here is what I know: The problem happens at all speeds and all RPMs. The engine appears to hesitate while accelerating, but also during idle and maintaing speeds. There is no check engine light on. There are no codes being thrown by the computer. There are no exhaust leaks. The egr appears to be functioning properly after testing it.

My remedies thus far have have been : Resetting the computer, swapping out the plugs and cops, and swapping out the EVR twice.

When I replaced the EVR the engine ran like a gem for about a week. Picked up the power lost and no hesitation at all. Since then, the problem returned, and I took the EVR back for a replacement, but the problem persists. It seems that when I replaced the EVR it triggered the problem part to function properly for a minute, but now I'm back to square one. My next step will be to clean the EGR, EVR, and DPFE lines free of carbon deposits, and hopefully that works.

Based on what I have described above, does this sound something else? I feel like I'm in the right area, but can't isolate the problem. Hopefully this info points you in the right direction to help me resolve the issue. Thanks!