First, what made you believe fuel pump was bad, and how didn't you find out it wasn't. Whatever tests you may have already don't will help me narrow down possible causes.
Also, are there any warning lights on the dash, specifically the check engine light? If so, that is where you should begin because having the computer scanned will point you in the right direction.
There are several possible causes for your car to run rough/misfire. It could be as simple as bad gas to as complicated as an ECU malfunction. If there's no trouble codes stored in your computer, begin your diagnosis with by checking that there's no water in the gas. Next check the basics like the spark plugs, air/fuel filters, etc.
If all of those are new, then you'll need to check that fuel pressure is good and that the ignition system is in good shape.
The fuel system consists of the pump, filter, regulator, lines, injectors and wiring/connectors. Check each component thoroughly.
The ignition system consists of the coils, spark plugs/wires and wiring/connectors.
Don't forget the ECU and sensors which tell control both systems. If a crank/cam sensor is faulty, you'll have a random misfire that will cause the symptoms you described as well.
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Tuesday, June 11th, 2013 AT 12:15 PM