Well, first of all, you shouldn't replace parts without confirming they are bad. Second, just because parts are "new," doesn't necessarily means that they are good, which ties into my first point. A possible catalytic converter/exhaust restriction issue can be easily tested by using an exhaust backpressure tester, which screws into the upstream O2 sensor (or, air/fuel sensor) hole. A suspected bad fuel pump or delivery issue should be tested with a fuel pressure gauge. Are there any stored trouble codes in the ECM? At some point, it will be necessary to view the ECM datastream and a compatable generic scantool or Nissan Consult II or III will be needed to do such. Without the equipment to do such tests, you are essentially working blind and you could spend a small fortune on replacing otherwise good parts. If you don't have the equipment, I would suggest you have a competant auto technician with the proper test equipment and tools diagnose the problem. BTW, is this a 1.8L? If so, you may want to check for a failed head gasket, as well. It's not an uncommon issue on these engines and they can cause cylinder misfire codes, which many initially mistake for bad ignition coil(s).
Last edited by smj999smj; Sep 24th, 2011 at 08:19 AM.