[cardoc]

Check the battery cables for tightness and no corrosion. If the cables are good, get a new battery and then check the alternator output. You may need both a battery and alternator.

The stuttering, clock and engine shutting down is an indication of a bad battery or connection often times coupled with a failing alternator. It could just be the battery.

 

[cardoc]

Don't rely on voltage. Check amperage output.

 

[cardoc]

The parts stores have a meter that test amperage output. It's the same meter they use to sell you a battery. It needs to be checked with the engine off. You compare the CCA rating with what the battery is actually putting out. If the battery is low, it would be useless to check the alternator performance.