Service engine soon light?

This can be an injector, fuel filter, low fuel pressure or a vacuum leak besides all other ignition problems. So you have to check for vacuum leak as well as low fuel pressure first.

Did you replace the wires along with the coil. Also, check the connectors/wires going to the coil pack for looseness/corrosion.

Has wiring to coil and voltage been checked? Spark from coil? What is code in P0xxx format?

When was the last tune up? Also, have you checked fuel pump pressure?

If the check engine light hasn't come on, I would start by removing a couple plugs just to check the condition. Also, check for vacuum leaks and make sure the egr isn't plugged. If the check engine light is on, let me know.
Joe

https://www.2carpros.com/dia/how_to_scan_trouble_codes.htm

You need the codes to procede. Find and post them.

235 miles?

You actually didn't need to change the O2 sensor for this code. This code is typically set due to either a lack of fuel or the presence of too much air. The O2 sensor is doing what it is designed to do by telling the computer that the mixture isn't correct. Check for an intake leak. You may be able to hear the hissing noise while the engine is running. Or you can spray a carb cleaner around the intake surface. If the engine changes, pinpoint where and that is your leaks.