My 2008 has been rough at idle since I got the truck. Changed out plugs, wires, injectors, etc but nothing helped. On weekend, changed my 4 02 sensors even though they did not trip an engine code. Truck is about 75% better now. less rough even though there is a small slight shake at idle, more power and went from 9mpg to 13. The next step is changing out the intake manifold gaskets or the manifold itself. But overall very pleased. Huge difference in truck.

 

Could be a leak on one of the intake gaskets. Also good to spray some cleaner (specifically for it) on the mass airflow sensor and maybe clean the throttle body and butterfly. That is hyper sensitive with the tiniest of a gap for metering the airflow at idle. Does not take much buildup to hurt idle smoothness.

 

MAF and throttle body were cleaned. I think intake gaskets are next. thanks for the input.

 

Only other place I can think might be a leak somewhere else on the intake. I know on the older models the fuel pressure regulator is mounted on the driver side with a vacuum tube to it. Old school method to check is to spray carb cleaner (I've also seen people say to use starting fluid but that seems dangerous, propane torch, not lit, is another I've seen) around the intake while its idling. If the idle changes that can help pinpoint a leak.

 

I fought a misfire for months on my 03. After a bunch of trips to the garage and maf cleanings etc. I got fed up of telling the mechanic that i thought it was the intake gaskets.
I replaced the intake gaskets with the steel fel pro ones. Problem solved.