I posted in the Super Duty forum but thought I would also try here. Truck is running rough, especially when in a gear. When driving the truck it can be real rough or slightly rough, but not normal. Coming to a stop light/sign the RPM's will drop to about 500 or so with a harsh idle, tach bounces around 400-700rpm. At speed (55-60) the truck will run ok until it drops into overdrive and then let the shaking begin.

I tried switching the cop from #5 to #1 to see if a code would follow it. I thought I felt the vibration move from drivers to passengers side but unfortunately it is still giving me a P0305. I've read about leaking vacuum hoses and such. Anyone with a 2006 Super Duty can you point me where to look, as I believe the 04's and earlier were different. Also I noticed a tube running from the drivers side valve cover, over cylider 5, running back into the intake. What is this? Also there is a lot of buildup of a black substance where this tube meets the cover. Is this normal? Any help info appreciated.

My plan is as follows

Try new cop on #5
Look for Vacuum leaks (just would like to know where to look)
Try new fuel injector
Try new spark plug


Thanks in advance for any help.