Update.. Check engine light on now. Still riding rough and no power with throaty noise on accleration. Also noticed the exhaust air is really, really hot and the cats and muffler crackling after turn off. Can even put my hand near the exhaust pipe its so hot.. Verified both side exhaust manifolds getting warm and eventually HOT together. I think both banks are firing. Brought it in today.. Mercedes Dealer Smithtown N.Y. I am about to bend over.. Will let everyone know. I wish I was able to fix her myself. I did everything but solve this problem. Thanks All