If you have ever replace spark plugs you can easily change the 6.0 plugs and it is NOT a 2 hour job for a skilled shop. I replaced my plugs and wires on my 6.0 a few months ago and it runs much better. There is a short set and a long set of plug wires because GM used two different coil manufacturers for a few years and their design dictates the length of wire you need...
see here (customer image at top right). I used ACDelco 41-110 professional iridium plugs at $5.70 each (USD). This is a $90 (US) project if you do it yourself. Each coil is above each plug so it's a no-brainer....no messing up the firing order. And yes, a clogged fuel filter can cause it to run rough. The filter is inside the frame rail under the driver and also easy to replace.
