Car is Too Lean

My car's been slightly hesitating off the line once in a while and the oil pressure gauge stutters at idle somewhat and reads about 60 psi @ 80 MPH.

This has been going on for about two weeks now. My SES light came on yesterday and stayed on for about an hour and turned off.

While it was on I got it scanned and the results were PO171 and PO174 (Too Lean in Banks 1 + 2). The mgr. at Advance Auto suggested it could be a burned out O2 sensor and someone also suggested to me that I have a vacuum leak.

What could cause the car to be too lean and how do you pinpoint and correct a possible vacuum leak?

vacuum leaks sounds like a high pitched whistle from what i have experienced with them, obviously yuo can just pop your hood and listen around for a noise similar to that

spray ether around the vacuum hoses if the engine surges it means it is sucking in the ether hense there is your leak. Be careful though cause its flamable!