4000X4 banda

Rail and regulated voltage remains the same.

Mute voltage where to measure?

Driver IRS2092s
The CSD pin voltage for three of the channels 3.85v and about 2 seconds it will pulse to about 10v

The other channel 3.7 and pulse to 7 every 2 seconds
 
Clipping without audio? I assume you mean that the clipping indicator is lighting.

Have you tried pushing on various components and the board to see if the intermittent problem was due to a possible bad connection?

Have you tried heating and cooling (freeze spray) the areas around the channel that's different to see if you could find a temperature sensitive component?

When the amp won't function, do you see excessive DCV pulsing across the speaker terminals of the channel that's different?