1997 Battery/Alternator/Voltmeter

I have a 97 with about 150,000 miles. About 2-3 weeks ago I noticed that when I would start the voltmeter would show about 9 volts then drop to zero. I would turn it off, start it again and I would get about 14volts, no problem. This became very sporadic, the gauge would show 14v and then zero and when I would restart it would show 14v again. Or sometimes 9v and then zero. I took it to two mechanics, the first said that the 90s' jeeps were known for bad gauges and I would need a new instrument cluster. The second said it was probably the gauge but tested the alternator and it put out 130+ amps so he said the alternator was fine. I drove it to work Saturday and the voltmeter showed zero. After about 5min of driving the radio turned off, the HVAC fan died and the window went up really slow. When I got to work after about 15 min of driving it wouldn't start. I took the battery home, gave it a deep charge and drove it home (voltmeter showing 14v). I then took it for a drive about 30min and voltmeter was still fine. I stopped at O'Rileys and had them test the battery and voltmeter and even though the voltmeter showed 14v the battery and alternator tested as bad. I took the alternator off and had them bench test the alternator and the alternator passed... I cleaned the connectors, and replaced the alternator. Today I drove it and same thing is happening.

Any ideas???