I had a mechanic tell me that fuel cleaner is not necessary for cleaning injectors as if they do a good job themselves. Certainly, around the manifold area where fuel enters as well as vacume line, they should be cleaned with an arasol spray. Gasoline by itself wont accumulate build up but notice your mixture screw by removing it and it may have lots of dirt. This is where air and fuel are mixing. Always, mark where the exact position of your screw is, mine bottoms out .6 turns after it's normal position.
