04 ranger v6 3.0L misfire under 1000 rpm
check engine light stays on. starts blinking, after a couple of minutes, when under 1000 rpm. 3 codes: P0316, P0420 and P0304 (misfire cylinder 4). Fairly new plugs and wires. Just changed plug 4 again but did not help. Runs great above 1000 rpm.
When you removed plugs ... were they brown, grey or black? Black could be worn engine or head gasket problem
Plugs looked good. I am sure the engine is worn some as it has 313000 miles on it. However, I have kept it in good shape running syn oil and changing it often. Most all miles are long distance highway miles.
Could it be the coil pack?
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