Hello, I could use some help please. My 2007 Outback 2.5I overheated  due to head gasket leaking compression into cooling system. I did everything the right way, I had the heads machined flat and used Subaru parts to reassemble. Upon initial start up it ran rough which is not a surprise. It had a rough idle and stumbled with throttle. Then CEL came on so I scanned it. That's when all the misfire codes came up. I cleared them out it ran perfect for a day until just now. Cold engine after work and the scenario repeated exactly. I cleared codes and drove home with no further issue. I reused my plugs and wires since they only had 15,000 miles and looked fine, And yes they are NGK . And this issue never happened before the cooling issue. Any help is appreciated, thanks.

Check all the electrical connectors you had to unplug. The big ones going to the engine can take more force to seat than you expect, one may be loose causing intermittent issues.

Good advice, thanks.