Ah, that's for certain a connector or harness that's loose. After I installed a Speedohealer in my Tundra, I had similar issues from time to time, especially when I hit a small bump. I took apart the dash I don't know how many times before I discovered that there was strain on the gauge cluster connector and if the conditions were just right, it would kill the dash electrics etc.

I'd start with the connectors at the back of the radio since you said you had it replaced recently. Anything that was "crammed" back into place when the dash was put back together would be suspect. A little kink or pressure can lift a pin and cause a temporary connection break.