Changed spark plugs and still has miss fire. Old plugs were black
My car has 88000 miles.
My car has a manual transmission.
A misfire can be caused for several reasons such as bad plugs (which you have fixed), detonation (bad timing), bad ignition coil, vacuum leak, faulty fuel injectors, low fuel pressure or faulty spark plug wires to name a few. This may require some specific diagnosis that will require the computer in your car to be scanned for fault codes which will indicate specifically what the issue is. If you need further guidance on this, a certified professional from YourMechanic can diagnose the misfire issue firsthand and assist with a repair.