Have you had the valves checked for adjustment? Misfires on these cars sometimes is related to valve adjustment or burnt valves. Could also be a bad plug wire or maybe the coil is starting to fail. Is the problem worse when you first start the car and then get better as it warms up? This some times points to bad valve adjustment of the exhaust valves. I would install new plug wires you can find someplace on line that you can buy Honda wires with out having to go to the dealer. See how it runs with the new wires, then have the valves adjusted at your independent mechanic. You shouldn't need fuel injector cleaner if you use good gas as most name brands put some in there fuel. If you have to put injector cleaner in only do it at the gas station and only use the right amount for the amount of fuel your tank holds. Put the cleaner in at the gas station and then fill it up. These cleaners are a solvent that will eat up the wires in your fuel pump and fuel injectors if used in to strong of a concentration. The fuel pump and injectors rely on the fuel to cool them and the solvent will eat up the wires if it is to strong.
Jeff