I usually idle at about 750/700 ish and now for the oast few days ive been idling at about 500/550. I checked my engine for a vaccum leak, and i dont appear to have one. I also just cleaned my air filter, and am not getting any codes for an o2 sensor messing up so im not sure what could be causing it. The car runs perfectly normal, its just that idle. When i start the car when the engines cold i get a normal start up, and the car idles at around 1k ish and slowly goes down to the 500. If i start it with a semi warm engine, ill get almost a weaker start, where the idles will shoot up to 1500 then almost instantly dip down to 500. What could be causing this issue?