As some of you know my 206 has been in the shop getting an annual and what turned out to be a top overhaul. Anyway the aircraft was done the end of last week and I needed to fly an extended cylinder breakin flight of about 2 hours. So after doing a triple pre-flight, 45 minute ground hold for departure, I left KADS at 9:30 this morning. Anyway, on the climb out over Love the engine starts running rough with what sounds like a miss. Looking at the engine monitor #2 has gone very hot relative to the other cylinders. So anyway declare and turn back. LOTS of traffic I'm right in the Love field landing corridor. Anyway, I reduced power immediately because if it seized I didn't want to be at high power and possibly tear the engine from the mount or other bad things. Anyway, I had enough altitude, brought it in high, and back to the shop for a cuss and discuss. The wife handled the cussing part with the service manager pretty well. So what could cause one cylinder to do that? Clogged injector?