my dam light keeps coming on the scan tool i have been using keeps saying misfiring cyclinder 5,,,i rep[laced all the plugs and coil pack in bank 5 even though i think it was fine and well the light keeps coming back on it's killing me i don't wanna give up and take it to the dealer and have them tell me the same thing that my scan tool was reading. i know that the truck does run better on the highway at full throttle but at idle it is still rough,,shakes a bit especially at a light in drive with the brake on,,,,,what is wrong with my truck someone please help i did replace the pcv valve and clean the iac valve....

 

Try switching the injector with another cylincer and see if the code moves with the injector.

 

Agreed and hoping thats it If it's not a Plug, Coil, or Injector, it could be something bad Also make sure you dont have a bad wire on Coil #5, (to the electrical connector) I've actually had this happen before and of course it will misfire.
Also pull coil wire #5 while it's running and see if there's ANY DIFFERENCE at all ???

Good Luck Bro, hope it's something simple...

 

Take out the plug and inspect it.
While your doing that do a compression test and compare the results with other cylinders.

 

I have the same issue! But mine was cyl #6. I replaced all plugs/wires/coil, and still here? what the heck is it?

 

The term misfire does not always mean an ignition problem. Misfire is just defined as incomplete combustion. A compression test and a Cylinder leakdown test would be a very good start. If the problem seems to go away as RPM goes up, your problem could be mechanical. Where as running the same or worse as RPM goes up would be ignition related.