Kia Troubleshooting Questions? Ask a Mechanic
HAve you pulled any of the diagnostic codes? I'm assuming the check engine light is on.
it sounds like you have a fuel volume problem i.e. fuel pressure or you could have a vacuum leak somewhere sucking in unmetered air that the mass air flow sensor is not seeing. Could have a tear in the intake tube between throttle body and mass air flow sensor, or a vacuum line, maybe even brake booster hose leaking. It is running better at higher rpm so may rule out fuel pressure but not fuel qaulity.
is there any noticeable smoke from exhaust? weird odor tends to make me think the quality of fuel is in question or a restricted exhaust.