Then I would just start a priority list of "things to check" starting with those that you beleive are the most likely.

Start with those you think are most likely first and work your way down the list one at a time. Do not make 2 different changes at the same time (unless you think a combined change is the solution) so that you can tell what effect each thing has.

Here would be my suggested list in order, but you will have to decide on your own.

1. Look and see if there is any easy dead weight that you can find in the plane to lighten it up.
2. Test for lateral balance, it cannot hurt and making it perfect will only make the plane fly better.
3. Double check you CG and do a trim test to make sure that you are trimmed out for hands off vertical downlines, knife edge mixes are right and how the plane flies inverted hands off compared to upright hands off. Ideally you want it to require just a breath of down elevator in a vertical attitude, specifically an inverted 45 degree upline.
4. One you do that, try again. If it still rocks, change the prop to maybe a 23x8 see if propwash is an issue.
4. If it still wingrocks, increase your elevator throw 5 degrees at a time and see if there is a point where it stops or gets worse. 45-60 degrees is usually the ticket.
5. Then once you have exhausted effort, try increasing your high rate aileron throw or adjusting expo on the ailerons to see if you are reacting too slow/too fast.
After that, either practice till it stops OR pull all of the gear out of it and have a Bon Fire...
Then go order you a new plane!!