I would not overlook the code shown. Check the wiring to the sensor and if it appears ok, maybe consider that the new sensor was bad out of the box. I remember on one truck I had, I was having similar issues with starting, but once started it was fine. The entire time it only had a temp sensor code, but I didn’t think that was the problem, chased 100 other things to no avail, then did change the temp sensor and was fixed just that easy.

In my vehicles, not a civic, but calls for 5w20, while I will run that in the winter, I run 5w30 in the summer because running 5w20 in the summer I find myself adding oil more often. For me, thicker oil for summer, thinner oil for winter.

A simple scanner would be enough to tell you if you have a bad O2 sensor, the fancy scanners are not needed for that. I would bet on your O2 sensors being ok. One thought that came to mind, is your temperature sensor ok?

If it is not overheating when you are cruising down the road and only when stopped or going slow then that tells me it is an airflow problem. Either new fan is not working right, radiator fins plugged up or shroud issue.

Shift cable maybe, if you are lucky.

You don’t have to do them both at the same time. Make sure you don’t have any exhaust leaks prior to the upstream as that could be the issue, if it is the issue. I would check for codes with a scan tool. If you have a bad O2 sensor, the scan tool should tell you.

Could be several things. It needs to be checked out asap by a mechanic. Sorry that isn’t a good answer, but if it’s a wheel bearing or strut that will lead you to further trouble if you let it go.

Are the wheels seated correctly and the lug nuts torqued properly? Sometimes that doesn’t get done correctly after someone has wheels off the car. You might be feeling that and not the brakes. Check your lug nuts before driving it.

Did you check for any fuel line leaks, check for any wiring issues? It is always possible that the new pump that you bought was bad out of the box (probably not the case, but I have run into this with new parts before). There is also a trick with a failing fuel pump, if it doesn’t start you can beat on the tank (without damaging it) with a rubber mallet in the pump location of the tank. Sometimes with failing fuel pumps, this is enough to get them temporarily working again. Don’t get hung up on just the fuel pump or even fuel system, maybe something else is going on. I would try to make sure the wiring to the pump is ok first.

Cheapest fix on worrying about fuel level is to fill the tank, set your trip meter to zero and then fill it back up at xx miles. Do the math to figure out how many miles you will get out of a tank full of gas, then make sure you fill it up 50 miles or better ahead of that. Example: car has 20 gallon tank and gets 20 miles per gallon, you know a tank full will get you approx 400 miles, so set the trip to zero, and when you see it around the 300 miles mark, fill it up again and remember to reset your trip to zero when you fill up.

As far as pumping gas in, cheapest fix on that is hold the pump handle upside down when filling the tank. So instead of the pump lever toward the ground, it will be pointed toward the sky. You will look a little funny pumping gas, but that should work for you. I am serious, this isn’t a joke, learned this trick many years ago from a gas station attendant when I had a vehicle with the same issue.