1999 Jeep Cherokee P0300, P0304, P0306, P0308 OBDII Codes

1999 JEEP CHEROKEE
156,000 MILES • V8 • 4WD • AUTOMATIC
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BILLSWEENEY
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  • 1 POST
Vehicle is running and has not stalled, but my MPG is very low and the engine run rough with poor acceleration.
I know the codes refer to misfire, which sounds logical.
Apparently, the first course of action is checking the coil connections and plug buildup.
My question is what are the proper top-of-the-line plugs & coils if I choose to replace them all?
Jun 8, 2009 at 1:06 PM
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RASMATAZ
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Engine misfiring can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.
Jun 8, 2009 at 4:19 PM