[STEVE-O]

Doublecheck the ground to frame connection in the trunk. I had a disconnect there that initially caused the speedo and tach to jump around.
May be worth a check even though you did say that you still had solenoid chatter.
Other than that, maybe the MSD quit. Seems like it would still crank though.
If not the ground, then sounds like low battery voltage. Keep a Battery Tender on it when not driving.