That's pretty high at an idle. Check it at 2000 RPM. if it's much higher than what you have, it needs a regulator.
For a real stater test you need an amp meter that can take 400+ amps.
For a good alternator test, you need a carbon pile load tester to get the max output.
A garage shouldn't poke...
Check the voltage on the battery as it sits. 12.0-12.5VDC is good. less than 11.5 is not. Recharge and start again.
Have someone crank the engine while you check the battery voltage. It's a real good idea to stand to the side as you do this as I have seen lots of my students try to start an...