Originally Posted by PrecisionAuto

Apparently you are not aware that inter gas (such as the exhaust gas flow coming through the egr valve) is not combustible. On that model vehicle the egr ports in the intake manifold tend to clog. When this happens it will leave all of the exhaust gas going to one cylinder instead of distributing across all four. This will cause a miss fire / stumble situation and cause a lack of power. But then if you new more about what an egr does, what functions it serves, and what may happen when parts of the system are not working properly. Then you may have known that. The only reason I mentioned it, is due to the fact that I have had to fix several of these.