I bought an 03 full size montero ls on the 30th of july. I have been combing and combing classifieds but never found one.

Well one popped up on cl and it was only 3 grand!!! for an 03 ls with 166k, so i called emailed and texted him imminently!! i went test drove it and bought it for 2900.
It was flawless with just a few minor causemetic issues and it even has new tags/plates, and new off road tires.... I know i got a hell of a deal but i am worried why. The only other LS i have seen around here are int he 6-10k range with higher miles.

Its a great vehicle, but has a few issues i am discovering....

It is very slow to start, and runs a little rough when started and idling.
the check engine light popped on and i had it coded and they said it was an 02 sensor.
How hard and expensive are they to fix, and how soon does it need to be done?

The drivers side window is lagging a bit and got stuck on me last night. I waited a while and restarted engine and it rolled up possible electrical issue??

Oh and its missing the cover that covers the third row seat when it goes into the floor.... i don't know the part name or where i can find one but i was hoping someone would know as i really would like to find one.