2005 Kia Optima loss of power

Is the check engine light on?
If so, please have the computer codes read at a local auto parts store. Post the codes here and I'll be able to aid you further.

An O2 sensor can cause some of the problems that you are having (once it gets bad enough). So please post the computer code(s) here so that we can advise you of the step-by-step process for determining the O2 problem which may very well solve the other problems you have.
Meanwhile please check all of your vacuum lines for leaks and check the throttle body to see if it needs cleaning.

Your P0320 refers to a failed ignition sensor. Attached is a picture of the sensors location. Often this is the cause of the type of problems you are having.

The P0442 is a Evaporative emission leak code. (Usuall associated with the charcoal canister ont he vehicle which stop gas fumes from entering the atmospheres. The most common cause for this code is a person not puttiing the gas cap on correctly (tightly sealing the gas tank).

P0122 is set when the TPS output is not in the 0.3v to 0.9v range at idle.

The ECU applies a 5v reference voltage to pin 5) then measures the voltage (pin 4). The actual reading is used as the idle position reference for the ECU. The ECU uses the TPS to adjust timing and injector pulse width.

The TPS is a variable resistor. The resistance changes according to throttle position. In the TPS housing is an idle position switch (grounds pin 2 when closed).

You need an OBD-II scanner or a voltmeter (pin 3 = +, pin 1 = gnd) of the TPS connector to set the TPS position.

The setup procedure is to loosen two screws slightly then rotate the TPS until the output is between 0.4 & 0.5v.

Tighten the screws. Verify that the voltage is correct then apply an epoxy spot to one screw head & TPS.

How'd you find that? Was the sprak plug wire grounding or one of the small primary wires?