There are some things to check other then CG although checking it again may not be a bad idea.

Control throws...Make sure they are all moving the right direction. Make sure they are not moving to much.( set as per instruction manual)

Engine thrust angle if your engine is pointing down toward the ground to much she no gonna fly so good.

Your plane while sitting on a level surface should be holding a near level attitude, or even SLIGHTLY nose up.

Make sure all your wheels are turning freely dragging wheels cause all kinds of issues.

The overall weight of the plane, if it weighs in much more then the instructions say it will, you have issues.

A plane that is not overpowered has to have SPEED on the ground before it flies. Always always always get a good roll before u pull up.

Finally....wait until someone that has been flying a bit can look it over..it will save you money..sometimes a lot of it..

Let the Hobby Shop guys check it out since you are going anyway. They may also have info you need on contacts.

There are others here that know a lot more about that engine and prop combo then I do...I hope they can answer you better.