Yes the SC has a problem with not getting enough gas to 3 and 6 cylinders has to do with fuel rail and where the fpr is on the rail ... This could make the engine vib...This is where the EGR comes in if you have one it recirculates gas fumes into the chambers to insure that there is some combustion untill the car is good and warm ... QUOTE]
EGR is exhaust gas recirculation it's already burnt dude. When it's reintroduced back into the intake it's to dilute the mixture and lower the combustion temp. This reduced NOx (emission) and allows you to run more timing advance at part throttle (the reason why people who block EGR port get part throttle ping). There is no way that exhaust fumes are going to richen the mixture for lean cylinders.
Stick to giving advice on what you KNOW.
Jerry