i bought my grand am in november with 90,000 miles on it.  a couple
months ago it stalled on me while driving 60 mph and i ended up having
to get a new key, tumbler, ignition, and everything re-coded which
cost me too much.  
now, in the last week my "service engine soon" yellow light came up
while i was driving and it has not turned off since.  it turned on
when i was at 94,950 and i have driven it 50 miles since.  i’m worried
about taking it in cuz i’m a poor college kid and can’t afford another
costly car repair.  the car sounds fine, doesn’t run any different,
and i don’t smell anything different either.  i have had no problems
since the light came on.  i heard that the light might just come on
when it hits a certain mileage.  any thoughts or ideas?