Yoke Causing Planes to Bank Slowly Left in Level Cruise

My CH Products Flight Sim yoke has always done this intermittently. Some months ago I talked with the good folks at Jetline where I purchased my computer and they thought the problem was caused by plugging the controller into a non-compatible USB socket. I placed it in an older style socket and the problem may have become better I think - not sure.

 

My CH Products Combatstick does not ever create this problem however. I can fly the same yoke equipped planes with the Combatstick and they cruise perfectly level without the banking. Not all planes exhibit this problem. I'm pretty sure it's not the fault of CH Products or the Control Manager. What did I do wrong and how can I fix this annoying problem without resorting to unrealistic passenger loading or aileron trimming? Neither of those two methods completely fix the problem.

 

Having flown real airplanes I realize there is no such condition as perfectly stable cruise but I'd like to get to that point initially with the sim and then introduce instability via changing weather conditions later.

 

I'm using P3Dv3.1 with Windows 10.

The two planes I used for this test were inherently unstable. One was designed that way and the other had a strange passenger loading setup leading to a large weight imballance. Many of my other yoke planes worked flawlessly. I did unplug the yoke and then plug it in after the computer was on. I will keep an eye on this but for now it may be okay.