Misfire? High mileage,well maintained car.

What is your question?

OK,I've changed the spark plugs,wires,intake manifold gaskets.Added fuel injector cleaner,and cleaned the throttle body.Searched for vacuum leaks.EGR holds vacuum ok. The car runs perfectly smooth,except on a start up and especially when I turn on the AC.-Then I get a sporatic misfire.Only code thus far was once last week when it only indicated "misfire within first 1000 rpm."Nothing this week.