Beyond doing the basics such as checking compression and visually confirming spark and fuel pressure (with a gauge). It's time to break out the scan tool and scope.
High mileage Honda's tend to suffer from the valves going out of adjustment. Take a look at MAP voltage either with a scan tool or by backprobing the MAP sensor signal pin. At operating temperature MAP voltage should be below 1v ideally around .8v. You could also visually confirm with a vacuum gauge off the brake booster hose. If map voltage is high and you have confirmation with a vacuum gauge you need to remove the valve cover and physically check each valve. Luckily Honda marks the cam gear so you know which cylinder is at TDC.
Another thing to check would be a short in the primary coil of each ignition coil. If you pull fuse 1 in the underdash fuse box and put in a loop you can attach a DC Inductive Amp Clamp and scope the current draw of all the ignition coils. It's best to get as high of a resolution as you can. I'll typically set the sweep time to 10ms.
A short in the primary coil looks like...
This isn't from a Honda but it's basically what you should expect. On the left the coil ramp is good. On the right you can see a sudden spike in current.
Regarding the head gasket I'd suggest doing a leakdown test. Honestly unless the car has a history of over heating and compression is good, this would be the second to last thing I'd check.
As for the last thing, It may be an injector, but I doubt it. Only on two cylinders and both at the same time? You could pull the rail and injectors and test the spray pattern and check the resistance of each injector. Or just swap them around to see if the misfire follows.
