Should I worry about old beer in Keg making off flavors?

I have a Belgian blonde that has 1/3 left of a keg I have. I kegged it in June of 2011. It has remained below 38 degrees since then. I am going to pour out or bottle the remaining bit because as you can guess, I wont finish it any time soon. I plan on soaking the keg and cleaning the line with cleaner/hot water. Should I be concerned/take extra steps to try and get it clean? Its a 9% abv beer and was brewed with a lot of candy sugar. It tasted pretty good, but I just dont want my next beer to taste like it. Thoughts?

going for it!

Your keg is stainless. As long as you clean it well you will be fine, as stainless does not pick up flavors from beer. There is a very slight chance your beer lines can pick up flavors, but unlikely.