measure the voltage across your battery when running. I think it should be above 13.8 volts.
If you take it in to a auto parts shop to have it tested, they only test at one rpm. I had a Grand Am that when you got above 3k rpms, the lights would cut out and all electrical had real problems. Tested fine at the shop. Brought it home and voltage dropped when rpms went high. Shop must not have turned the alternator fast enough to produce the problem.