What you're feeling is pretty "normal" for a bike set up with a China engine. If you pull the clutch in when you are slowing down it will go a long way in smoothing the ride.

These are old-tech piston port engines and the break between a 4 cycle and a 2 cycle depending on how they are "loaded".

If you hear a staccato sound while at cruise that changes to a nice even pull when speeding up or going up hill, then you've got the carb set about right.

Just pull the clutch as soon as you back out of it when stopping or going down a long hill.