You might try posting the question here: http://www.kenwoodforums.com/viewtopic.php?f=5&t=445
Sounds like a bad connection someplace, Conrad. It flickers only while the coach is moving? That's usually a giveaway that there's a loose power or other cable somewhere. With the unit on and the coach parked, engine off, manually manipulate any cables going into the device, all along their length, to see if you can replicate the problem and isolate a bad spot in a connector or a damaged cable. I'm not familiar with your GPS, so if it's in-dash, obviously you may have to make some effort to access the back of the unit and its cables. If there's an in-line fuse, check for corrosion or contaminants in the fuse holder.
Another place to look for help anytime you have a 12 volt electric issue is: http://www.the12volt.com/
Hopefully it's as simple as a loose, easily adjusted connector.
-Joel
