Cheap SH engines aren't bad, but don't last an overly long time. XTM used to run those engines and I think redcat runs them too these days.
When I had a rig with that engine in it, I replaced it with an OS18CV-R(X), was a nitro mt.
Yeah, that carb sucked balls. About all you can do is find a happy medium between too rich and too lean, then adjust the idle screw to bump it up a bit.
Then hope the engine breaks so you can get one with a proper 2 needle carb on it.