Heater core might be clogged internally, causing issues. Really shouldn’t be that on a newer car but shit can happen. Power windows not working is not related to this issue. Misfire, shouldn’t be related… Hoping it’s not a bad head gasket, but theres no way of knowing until it gets a leak down test of the cooling system and the block. Mechanics can test that cheap. Unless you have all the tools

Change the oil at 226k miles? Got it. Thanks :)

If it’s code p0171, I’m almost certain It’s the intake gasket. Very common on these. But lean codes can also be caused by vacuum leaks. That could be why the engine is shaking. These engines really shake bad when There is a vacuum leak. It can also be why the MPG is bad. That’s my guess, but could be a clogged injector causing not enough fuel to enter. Tons of things it could be. MAF sensor it could be. Can’t just be 1 thing throwing parts at it. Must be diagnosed in person