Air leaks usually raise; or cause a hanging idle if the throttle is blipped. So cant see it being that either......
Do these cars have an Idle Air Control Valve ?
**Cleaning the filter will be cheap insurance for sure. For many reasons !
After bit of looking I saw one of Foxspeed's comments saying these cars don't have Idle Air Control Valves, just the throttle body.
Had a quick google and apparently you can visually tell if K&N is dirty as it has darker sections on the side where the air is sucked in through.
Had a look at mine and there are no visually dark patches... this either means the entire thing is filthy, or it's reasonably clean... lol think I'll just give it a clean anyway!