I have 4 of them in 2 twins and they are great little engines. Once adjusted, they need very little changing. I have 11-5 APC props on mine right now.

Sounds like you have a low end mixture problem.

Start your engine, idle it down leaving the battery on. Pinch off the fuel line and listen. If the engine quits fairly quickly, your low end is too lean, open it up a quarter turn and try this.

If your engine runs for a few seconds, then speeds up a good bit, it is too rich. Turn the idle mixture in a quarter turn and try.

It should speed up slightly, then die.

As for the top end, peak it out, then open it up 3-4 clicks. You should have a nice smoke trail for the first couple of minutes of the flight. The engine leans out as the fuel burns down, so you need to set slightly rich at first. If you want to peak the engine, only fill the tank a quarter full, then peak the engine. Fill the tank completely, but don't touch the needle.

After the engine is set, you shouldn't have to change the needle unless you have a really humid day, especially a foggy day. High humidity will give you a rich run. Lean it out a few clicks, but don't touch the low end. You'll have to re-do it when the weather dries out.