Nissan Repair: 98 Nissan Sentra, nissan sentra, electrical inspection

Question
Ive owned my 98 Sentra for 2 years and it has always been very reliable. About two months ago, I went to start it on a cold morning and the battery was dead. I assumed my teenager had left lights so I had it jump started, ran fine, few weeks later, same thing. Put battery on a charger, worked fine for weeks. Last week the engine started to cut out and die while slowing to a stop, but would start up again immediately, with full lights and power. Also I could feel the engine cutting out when driving at about 35-40 mph. I have taken it to a garage, the mechanic told me he had driven it and it didnt do anything while he was driving it - said it could be a modulator (??) and that I should take it to a dealer. Someone else told me it may be the alternator - but do alternators go bad over an expanse of months? Im a broke single mom and dont want to put any money into this car that isnt necessary. Thank you so much for your help!!

Answer
Lauren,

I would go to Autozone or Checker and get a free electrical inspection.  They will let you know if the alternator is indeed going out.  Yes, if the brushes are worn they will slowly get worse as they wear out.  So, it could be the alternator.  But, from what you are saying I am betting the disttibutor has a worn oil seal and oil is contaminating the optical shutter wheel.  This is located under the cover that is under the cap, rotor and rotor post.  So, first get the free electrical inspection.  Then, check the distributor.  Email me back with what you find.