[Fixed]

Mr.Subaru has just posted a video of the DIY carbon build-up maintenance procedure. With his closing comments in mind this looks like it's a fairly simple and straightforward preventative procedure.

I try not watch videos usually it’s just to see what parts look like writing on parts and what not to do. Most shops use bg upper intake combustion cleaner it’s a three step process usually. I personally like to swap plugs after the tanker gas. Step on check air filter clean components maf maf cleaner if applicable. Step two take of air plenum or boot to throttle body. Clean throttle body completely with throttle body cleaner. Step 3 put back together and find a vacuum line or spray through the air intake. Spray upper intake and combustion cleaner not the sea foams lube. Why I suggested precleaning to first. You want velocity to cleaner that will eventually disperse into combustion chambers not all collect or dump in one cylinder. Also watch out for intake runners if applicable. Step 4 add fuel system cleaner and drive tank full of bg44k. Step 5 replace plugs and reset adaptive learning if applicable relearn all values or let idle and drive. You can relearn at any point tb needs new values. Boom done .