96 accord missfire

my 96 accord ex vtec misses at cruising speed 2000 to 3000 rpm. it starts fine, idles fine and has good power. code scanner says it has a missfire in #2 and #4 cylinders. i changed the distributor cap, rotor button, plugs and wires but it still does it. it accelerates fine and has plenty of power. any ideas? im going to try a fuel filter and see if that helps. thanks.