Hey, Sounds just like clogged EGR ports. Common problems on these cars. With the engine running, hook a vacuum pump to the EGR valve, the engine should die. If it doesn't die, or at least almost die, you have clogged ports. Cleaning them is a real pain, probably not something you want to try on your own. May require removal of the intake manifold. I can clean them without removing the manifold. Still, it's a pain & takes several hours. Let us know how it goes.