Hi,
About 3 weeks back, my 1999 Nissan Altima, suddenly stopped when I
was at a traffic light. The check engine, brake and battery lights all
came ON. I turned off the ignition and turned it on again and it
started fine. This happened often, when I am at a light or a stop
sign, but all the times the car would turn back on fin. I took it to a
mechanic, but they were not able to find any issues with the car.

For the past week or so, I have not had any problems. Now suddenly
this evening on my way home from work, JUST the brake and Battery
(charging) light have come ON and they stayed ON. The car did not
stall on me, but it feels as though the car is struggling to pick up
speed. It almost feels as though the engine has to overcome some
resistance to keep the car moving. I hear a sound, something you would
hear when the engine is working too hard.
Does anyone have any ideas what could it be? Could it be the
alternator? I wonder why the mechanic (who is a good mechanic) could
not find anything in the first place.

Also, is it better to take the car to a Nissan Dealer or would any
mechanic suffice?

Thanks
Prabhu