It's most likely the Idle Air Control (IAC) valve solenoid. It is attached to the throttle body right under the round air intake hole. It's black in color and has a plastic housing. It's attached by two screws. Do not lose them.Time to check things out again. Pulled into a parking lot and when coming to a complete stop the engine stalled. Started it back up again (starts and runs fine in drive, but stalls at stops), it sounds like a rather loud vacuum leak. May be time to start looking for new vehicle though, I'll know for sure after looking it over tomorrow after work. Kinda looks a bit like a leaking head gasket (front, near radiator). So that will mean new head gaskets and timing belt. May not be worth it any longer at this point. Especially since it could also use new brake pads and rotors among other little things.
I have CEL back on and the only code it's throwing is P0431 indicating an issue with catalytic converter. It did throw a code for cylinder 6 misfire after changing spark plugs and new vc gaskets, but not throwing the code any longer. It does vibrate quite a bit, so I'm assuming the misfire is still there.
Goto rockauto and look for 2003 to 2005 Sorento. It has the same engine. Look under "Fuel/Air' and then IAC. It's not cheap. When Sedona reached high mileage, this thing fails. Lookup how it works but basically it lets air into engine when stopped at light (throttle body butterfly is closed when foot off gas and foot on brake) so that engine does not stall. And the valve closes when gas is applied. You will stall at stop sign or light if this fails. Sedona throttle body is a pretty solid piece of machinery and is very reliable. No need to replace that.
Weirdly, Sedona Kia does not sell this individually for Sedona but does for Sorento. For Sedona, you have to buy the whole throttle body with it - mega money.
I did fix mine with this by buying the Sorento part and replacing it. The old part, even if you clean it won't work and will fail again. Do not buy one from ebay for Mitsubishi engine (cheap) - they say it works but do not believe it, I did and it didn't work, the part was like $25. money wasted.
You will pull your hair out trying to find out what's wrong. I did. My sister got stuck in places due to this thing failing. It was really annoying.