I recently had reason to pull the heads off the 3.5 motor of the 2007 Sebring. REASON: when checking for timing mark alignment (I changed the belt) the engine stopped rotating. After looking down the spark plug holes with a camera I found so much crud (Black/brown grainy, oily) in all the cylinders that the pistons would pack this crud up against the heads and it was so thick that the engine would not rotate. No codes are set. Is this a bad EGR valve?