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if it is sputtering you have an ignition problem and that will be in the wires,cap,rotor, although they look fine and they aren't also change the fuel filter and your problem should be solved.,,,,,

Is your check engine light on? If so have it scanned I believe autozone still does it for free. If you changed the plugs and wires check the distributor cap and rotor. These symtomps you are describing can be several different things such as 02 sensors or wiring or fuel filter or fuel regulator or you might want to double check that you have the plug wires going to the right cylinder you never know you might have made a mistake when changing them.

I would go with the fuel filter and see if it improves. If not, then you really need to get a close look at the ignition system. something like a bad coil or cracked ignition wire would do what your telling us.....gl

hows the air filter?did any check light come on?