l changed spark plug.injectors.fuel pump .the problem still misfiring

If you know what cylinder you are having a misfire in, try changing your spark plug wires between two different cylinders. (i.e. - if cyl 3 is misfiring, swap wires to cyl 3 and 4 AT BOTH SPARK PLUG AND DISTRIBUTOR and see if the misfire follows the wire) If this occurs, you probably have a bad wire.

It might just be a good idea to try replacing the wires anyway, they do not last forever and they're pretty cheap. l hope this helps you out, good luck! :)

If everything was done by you, it is time to send it to an experience tech. Find a tech that knows how to use scan tool to monitor misfire count & can read other engine running condition to narrow down problem area.
You did replace spark plugs, injectors, fuel pump but did u check ignition coils? Is there other code stored in memory?
There r few basic things u can check before send it to a shop..
check for air leak.
Overfilled engine oil may cause random misfire.
Dirty fuel filter may cause lower fuel pressure & result in random misfire ..