Good morning sir!

I have an automatic 2008 Scion tC with over 214,000 miles. I noticed that the RPM fluctuates a bit at start up. After the engine gets to operating temperature (usually 7-10 minutes), it stops. About 3 months ago, I changed all the spark plugs and replaced one of the ignition coils twice. The first ignition coil was faulty and indicated that cylinder 1 was misfiring, but that wasn’t the case. Fast forward to now and this is happening. I’m thinking maybe the mass air flow sensor, the throttle body, or the O2 sensors? Or maybe it’s something completely different. The vehicle fuel efficiency has decreased some. I’ve scanned the vehicle and no codes show up besides a constant faulty TPMS sensor that I need to replace. I did see that the long term fuel trim % tends to be above 11% when the vehicle is parked. Another oddity I’ve noticed recently is that when it gets colder (usually below 60 degrees Fahrenheit), the tachometer is all over the place and doesn’t display the proper RPMs. I can be going 50+ mph and the tachometer shows 0. This morning it almost felt like it wanted to stall for a second before it corrected itself. I hope I was detailed enough. I have two videos showing the idle that I’m referencing if that helps. I look forward to your reply. Thank you so much for your time and help!

LG