I have an 06 ext cab long bed that developed a huge number of problems last week. It started with a small knock that slowly got much worse,checked balance rates and #7 was way out so I replaced it,acted fine for about 5miles and it all came back again. A few days later I fired it up after work and the truck sounded like it had a lope tune and threw 2 codes for misfiring #3 and #6 within a mile of leaving it then developed a horrible vibration on the bottom end of the rpms but once you get it above 2000 it clears right out.I've never tuned the truck but I'm fairly certain that it had a small tune on it when I bought it judging by the amount of smoke and the way that it has always ran. any help would be greatly appreciated.

*balance rates are all over best one is -4 and the worst is showing -14 but I have a hard time believing that the all went out at the same time

 

Check the injector wires,my buddy had the same problem on his 05' though it was his injectors,turned out to have a short in injector wire!