Well if you are going to throw it away let me know and I'll send you my address.

This sort of problem is usually a tuning issue, either you or some other well meaning person thought that they knew how to tune the engine and then really foulled it up.

If you can I'd reset all the Carb settings and retune, if you are not adept at this, find someone that is.
Other reasons include (but are not limited too) dirty carbs, holes in the fuel lines, poor back pressure, loose engine mounts, unballanced prop, foaming fuel, too little oil in the fuel, running the engine too lean and so on. [&o]

Engine problems happen, a part of this hobby is learning how to deal with them, if you don't like that fact - then stay on the Flight Simulator and keep pressing reset.