I have a 2005 Toyota Matrix 5-speed very similar to yours Scotty with about 160k miles. Some days for no obvious reason, it idles low and rough and the throttle becomes overly-sensitive. You push the pedal a little and nothing happens, and then you put a tiny bit more pressure and the engine suddenly revs up. It seems to frequently occur on dry days with low humidity. I have replaced the belt, spark plugs, air filter, battery, and had autoparts store test the alternator with their meter and said it was working ok. What could be causing this? I even have to use the clutch a bit differently when the idle gets wonky, giving it extra gas to prevent it from wanting to stall when I start out on 1st gear. I really appreciate you and your channel and have learned a ton from your videos. Thank you!

- Todd from Lincoln, Rhode Island