Now Now Lee that wouldnt comply with emissions testing..... LOL
If the valve is mechanically stuck open and letting exhaust gas into the intake when it shouldnt be there it will definately cause the engine to run rough. What normally happens is a small chunk of carbon (or PISTON) will get lodged between the valve and the body itself which causes the egr to be stuck open and allow egr flow when there shouldnt be any. This is easy to check by taking off the egr valve, just two 13mm head nuts, and take a small screwdriver and push on the plunger in the middle. It is spring loaded and should be in the seated position after pushing on it.
