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
To add to the confusion the truck started up and ran just fine yesterday. This is the second time its gone from stumbling and rumbling to driving fine this winter. Drove it again today and it feels fine. I havent driven it a lot this winter so maybe there was some sort of fuel issue (water,ice,old). I'll be keeping my eye on this and hopefully it was just a hiccup.
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