Taking the head off is not that difficult but not something to be considered lightly. You need to do a lot of prep first like getting ALL the tools and parts e.g. gasket sets, new head bolts etc. Plus, all sorts of things can go wrong when taking the head off... A manifold stud could shear off for example. Therefore, unless you've got poor compression (get a test done), I wouldn't take the head off just to de-coke it.
In terms of a procedure, haynes has a very good step-by-step process.
IMO... Unless you've got smoke and/or poor compression, or head gasket issues, the sluggishness will probably be due to something much less serious like a temp sensor, timing, fuel pressure, the WUR, CO2 setting, or an ignition issue... Something like that.
Good luck!