No Starty

[badluck3000]

Ok I got this car from my mechanic it has been good for about 6-7 months and yes I have been told it?s a bad idea to buy a car from a mechanic. Anyway it every know and then when you get into start it, it just wont turn over it just does the er er enr. I take it into the mechanic
there not sure why it every 3 or 4 months wont start they clear the engine warning light mess with spark plugs, battery get it give it allot of gas and all be damned if that little 1989 stanza doesn?t fire right up for them it will run fine for about 3 months then the engine light will come on and about 2 weeks after that it wont start.
Then tonight I started it ran fine earlier in the day drive for about 1 min as I am about to turn onto the freeway my console lights dim then my power steering goes out and the lights in the car and headlights go out.
I am not a car person I have been trying to get through college I have went through 4 cars and about 5,000 dollars in mechanical cost does anyone have any ideas here cause its hard enough being in college with a piece of crap car.

[BoOCh_nse]

have the alternator, battery cables, and alt. belt been checked? it is possible that the alternator was not charging to its full potential because of a slipping belt or bad internal voltage regulator. this may have lead to a "slow" death of the battery. Has the oxygen sensor ever been replaced?