Like the other said, start with cleaning the throttle body. It's the least amount of cost (carb cleaner, I've even used gasoline), and is well worth the time with significant results if not cleaned in a long time (or at all). While you at it clean the IAC (idle air control unit).

Then you can move to items like fuel pressure regulation (FPR; see FAQ section of brickboard), new plugs (see if carbon coated), IAC and new injector seals. You may also want to check you intake manifold gasket for leaks (see FAQ).

Hope this helps

Gary