I own a Nissan Altima from 2001, for the past several months, I've been experiencing times where the car occasionally hesitates to accelerate, when it's at a low speed or fully stopped (such as a light or a stop sign) it revs little to sometimes hard, and sometimes it even stalls (shuts off).

I looked around online for people that had the same problem, usually its either a vaccuum leak, the spark plugs, or the Idle Air Control Valve.

What's the best auto repair shop to get this fixed?

Where are each of these parts located in a car?

How much will it cost to get them repaired?

Is it easy to fix the Idle Air Control? What kind of tools will I need?