Random misfire on all cylinders

When you did the tune-up, did you use OEM parts, or something else? I always suggest using original equipment when it comes to ignition systems. This is because a slight difference in spark strength can make a world of difference.

At 189,000 miles, with new plugs and wires in it, I might suspect that you are having problems either with a bad/weak coil or old injectors getting clogged up. There is a school of thought that says that cheap gasoline with a high ethanol content (maybe 20% ethanol) will eventually gum up the injectors. I am not 100% sold on it though.

So the next thing I would look into is checking the coils. Here is a guide that will help you get started there: https://www.2carpros.com/articles/how-to-test-an-ignition-system. I know yours is not exactly like this one, but I get the feeling that you have a good enough understanding to apply the article to what you know. Also, you will need a multi-meter to check resistance. Resistance should be less than 10 megohms.

If you cannot check it that way, you can get a spark tester from Autozone or Amazon and check the sparks at the cylinders. You will be looking for a miss at somerpm range. A miss could be absolutely no fire for a second or so, or just a weaker looking spark. Here is the spark tester that I have: https://www.amazon.com/Lisle-20610-Inline-Spark-Tester/dp/B0002STSC6/ref=sr_1_3?ie=UTF8&qid=1501325755&sr=8-3&keywords=spark+tester

So try that and let us know.

Ahhh good. That'll do it, but it's not the most obvious fix. FYI don't be surprised if the other one goes soon. Generally, when one O2 sensor goes, the other side goes within a few months, because they have the same age on them. I always order mine from Amazon or RockAuto and save about $20 over AutoZone/Advance Auto.