My 1.6 16v RSi is idling rough and quite low once the engine has warmed up, on cold start the idle sits just under 1k and runs smoothly then once it’s warmed up the idle drops below 500 and is quite rough to where you can feel the engine shaking a bit. I’m guessing it could either be plugs/coils, lambda sensor or another sensor (possibly map sensor or tdc?). The car drives fine with no hesitation however it seems to be getting slightly lower mpg than usual. Can anyone point me in the right direction of where to start diagnosing this issue before I start throwing parts at it? Thanks in advance.