97 Accord with 265,000 miles started to misfire on #1 cylinder. Changed plugs, wires, coil, distributor cap and button. Swapped the #1 and #4 injectors and still have a misfire on #1. I feel that I may have an internal engine problem. Is there anything else I may have missed or haven't tried?

 

done a valve adjustment lately?

 

I would clean out the egr ports, the plate, and the egr valve, and if that doesn't fix it I would do a valve adjustment.

 

Check compression first