PSI gages bouncing from 90 to 135psi

[SquareOne]

Such a rapid drop and recovery can certainly be contributed to an electrical issue, that is, if your air tank gauges are electronically controlled. The ones in my Cascadia are analog with air lines ran directly to them so they read whatever pressure is in the tanks, whether or not the key is on or off.

I thought you mentioned in your earlier post the governor pops your air at 135psi. If the governor is causing the air to pop continuously, then you have an air leak somewhere. If the gauges are dropping but then quickly recovering with no air popping, then I'd venture to say you have a momentary false reading.

**If you do have electronic gauges, maybe start with the sending unit at the tanks to see if there are any issues with the harness or plugs.