Flashing check engine light, cylinder misfire

Can you provide the exact codes that you are getting so that we know which cylinders are misfiring? Then we need to review this guide because there are a number of other things that can cause a misfire.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

The flashing engine light means that there is potential damage being done to the exhaust and engine systems as a result of the misfire so we don't want to drive the vehicle until we figure this out.

Lastly, when you say there is a coolant leak, is that an external leak or are you loosing coolant and have no external leaks?

We are going to need to get more info from here in order to figure this out however, let's start with this and we can determine next steps. Thanks

Okay. You said it was a 4 cylinder in the subject line. Did you mean a 4.0L? Otherwise it would not have a misfire on cylinder 6.

Either way, I would highly suggest not driving this until we get it fixed. I think you are doing major damage to the exhaust and engine if you continue to drive. The coolant leaking into the oil is the sign of a head gasket. At this point, if you repair the head gasket that may be all you need to fix. However, if you continue to drive it may need an entire engine.

Let's confirm the head gasket is the issue. Here are a number of guides that will show you how to confirm a head gasket:

https://www.2carpros.com/articles/head-gasket-blown-test

https://www.2carpros.com/articles/coolantantifreeze-in-the-engine-oil

https://www.2carpros.com/articles/how-to-test-engine-compression

Okay. That sounds good. I would definitely run those head gasket tests in the guide that I attached prior. Once the head gasket is confirmed then run the compression check so you can see which bank the issue is on. It is unlikely that it is both banks so I would want to find out which side so you only have to do that one.

Let me know what questions you or he has. Thanks for the update.

Okay. Thanks. Keep us updated.