I've had this same problem myself. My first 2 controllers had no problem whatsoever, but when I added a third, it couldn't hold still on the screen. We thought at first the controller itself was damaged. What we've come to discover, is that most of the time, it has to do with the angle you are at from the screen, or rather the sensor bar. There is a sweet spot of about 45 degrees, and anything outside of that can get jumpy or shakey. Functional, but shakey. If your position is going to be chaning, consider rotating the bar.
Additionally, try to keep lights or reflective surfaces that can cause glare, away from your TV/sensor bar. Example: at my parents house, they have a lamp behind the tv. When that was turned on, it was being read as one of the points on the sensor bar, and was causing interference. When the light was turned off, play went back to normal. Make sure you don't have any lights reflecting to the point that they are being read as a primary point.