Engine is misfiring?

Have a 1998 accord ex vtec 4cyl. Im getting misfire codes for a couple cylinders(cant remember which) but im also getting the random cylinder misfire code. It idles and runs fine when the engine is still cold up until it reaches normal operating tempature. Once its hot and still on idle, it misfires and shakes, the whole exhaust system shakes. Its not constant but happens every 4 to 6 seconds. Twice as bad w/ AC on, almost feels like its going to turn off. Accelaration feels slugish. I can feel and see the sudden drops in rpms every now and then during accelaration and when cruising at steady speed but AC can be turned on without any noticeable increase in misfires though I have to turn off the AC at every light until I start moving again.
It was so bad that I couldnt drive it safely but since then ive fixed a huge intake leak, cleaned the injectors, replaced the rotor, spark plugs and wires are good and replaced the knock sensor.
All these things did make an improvement one by one and now my mechanic is saying I might need to replace the distributor cap or the whole distributor. What would your advice be?