RE: Wing rock, dutch roll?
The other posts have pointed out the two most likely culprits: dutch roll or wing stall. Dutch roll is usually caused by a combination of low directional stability and high dihedral effect. Dihedral effect is the tendency to roll due to sideslip. The two sources of wing rock can be hard to tell apart visually because they both tend to occur at high angle of attack.
What you need to do is eliminate one possibility so you know what you are dealing with. The easiest tempory fix for dutch roll is to install much larger vertical tails, preferrably on the bottom of the fuselage. If you put the enlarged verticals on the top, you may be increasing the dihedral effect faster than you can increase the directional stability. If the rolling stops, then what you had was dutch roll. If the rolling does not stop with the larger verticals, then you have post stall gyrations.
Dick