2011 Ford SVT Raptor 6.2 4x4 with idle issues

[MurderedOutSVT]

I would pull a plug and see if it really was changed/how bad it looks now. Could also be an injector going bad. Those are fairly cheap and pretty easy to get to

 

[Ruger]

Inside the plug boots beneath the coils is a spring that insures proper electrical contact with the spark plugs. Those springs can fail and have been found to be subject to rust. That's one thing to check. They're not expensive in the slightest and are not difficult to replace.

Another thing to check are the ignition wires that run from the coils to the lower banks of plugs. One or several might have failed after 11 years and 108K miles, and one or several might not be properly plugged onto the spark plugs. It's tough to get to them, and it may simply be a connection problem. If you think you need to replace those 8 ignition wires, a good choice is MSD #31639 - $89.99 at O'Reilly Auto Parts, and $89.91 at Summit Racing.

 

[Sozzy12]

Do a compression test on all cylinders to rule out internal issues. Any odd noises? Collapses valve springs are possible. The K&n open elements suck in a lot more dirt than the stock box. Clean the MAF sensor, throttle body, intake tubes, etc. Rings and valves could be toast from ingesting extra dirt. Check for vacuum leaks too.

 

[BenBB]

I agree with others, would check those two cylinders for 1) broken valve spring (not that hard to pull the valve covers, just get it clean first, there's a ton of youtube videos on replacing a spring if you need to) or 2) coil/wire/plug issue (also easy to pull 'em and see). Sounds like you're on the right track but I would focus on #5 & #6 now that the rest cleared up, good luck!