Need help on motor missing while driving

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Dec 1, 2011 | 09:02 PM

TWDITMORE

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Need help on motor missing while driving

Need some help folks. My truck has started missing while driving check engine light came on today had it checked and dont remeber the number however it came up with HO2S21 and PO303. 97 5.4L
I think that is is O2 sensor Bank 2 sensor 1 however the p0303 is missfire cyl 3. Now my question is should I change the sensor or should I change the coil pack. When driving engine runs fine and will just start missing and then go back to running like normal.
1997 F150 5.4l 4x4
THANKS
Tim

Dec 2, 2011 | 05:42 AM

RaptoRx7

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I would address the misfire first, then have the codes scanned again if any remain...

Dec 2, 2011 | 07:24 PM

Bluegrass 7

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A missfire is never due to an OX sensor.
Could be a faulty coil/boot, plug or moisture in the well.

Dec 3, 2011 | 09:50 AM

SwOkcOffRoader

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From: okc

A misfire can cause an O2 sensor code sometimes. Change your plugs, and check the coils as you go, look at the plug boot for holes, sometimes they rot and spark finds a way thru.