welcome barry, it is a common egr issue, you need to replace the mushroom valve, if you open the hood and look at the intake manifold it is a small mushroom looking device on the drivers side, they cost about $60-$80 to buy and its just a a couple of small hoses and bolting the new one in. do a search of this site and it may yield a picture or check lexls.com, they may have a tutorial on the subject.
Thanks for the reply. Got any websites I can buy the valve from? I am 100 miles from a dealer. Barry