Crossfire is over rated and I wouldn't run a multi gpu setup again myself. Having said that I'd have to recommend turning on frame pacing in amd radeon settings and v sync on the application. See if that helps. Sometimes, the multi gpu setup is firing out so many fps it causes tearing and stuttering because your monitor can't keep up.
Oh and one more thing. The crossfire setup will create a lot of heat and gpu will throttle, slow down, once it gets too hot. This can cause the device removed error. Your gpu throttled so much windows reads it as removed. Please install MSI afterburner and set custom fan curve to keep the temperatures down.