leave the stripping down and repairs to an expert its not a job for a novice, if its losing that much fuel you should be able to see where its coming from. also if you put your location on the thread some one could be close by who could look at it for you and even help you by recomending some one, there are a lot of **** takers in the forum but always willing to help.
It can only really leak from throttle shaft seals, inputs or outputs or the seal between the top of the body and bottom. If it's a leak from a seal they can almost all be changed in situ.