On a 99 the wires and plugs are underneath a cover on top of the cylinder head that is sercured down with allen headed capscrews (5mm hex). If you take the cover off, you will find two coil packs and two plug wires (each coil services a spark plug directly and another via a plug wire).

The mass air flow sensor is on the driver's side of the engine bay, between your intercooler and intake manifold on your model in the intake piping. They are prone to getting contaminated with oil on your model due to a design nuance. Failures in the air mass sensor tends to generate check engine lights and crappy running (misfires and poor throttle response).