Have 2007 Dodge Mega Cab 4x4 with 57k miles. Has engine vibe/shudder at idle. Dodge replaced 5 injectors and still had vibe. They removed engine and head and inspected and supposedly found no problems. Chrysler recommended replacing 6th injector and that was done. Still have vibe/shudder at idle. Truck can use low and high sulfur fuel so I do not really know which engine I have. Any suggestions, etc. to what the problem is?