HELP! =[

1990 Nissan 300ZX • 6 cylinder 2WD Manual • 197,000 miles

Enter your question. Car runs rough through 1500-3000 rpm, bucks after the 2nd and 3rd shift.
misfires on one cylinder (5),
sometimes has some backfire,
pulled codes, only has a 13.
which is the coolant sensor, I bought a new one, was a duralast, and no change. Im so confused and frustrated, please help me!
its a 1990 nissan 300zx
thanks so much
March 27, 2011.

Check the no.5 sparkplug, compression and injector. Could also be caused by the following below

Oxygen sensor.
Catalytic converter.
Fuel injectors dirty/sticking.
Mass airflow sensor/Airflow meter.
Throttle position sensor.
Crankshaft position sensor
Knock sensor
Manifold absolute pressure sensor.
EGR Valve
Fuel pressure regulator leaking or defective fuel pump.
Fuel contamination.
Foul/defective spark plugs.
Open spark plug wires.
Ignition coil/Coil packs defective.
Incorrect ignition timing.
Cap and rotor.

Note: If it doesn't apply disregard it and keep testing.

Mar 27, 2011.