I have a 98 chevy cheyene 4.3 L with a miss on cylinder 6 can't fix it

When driving I get a miss at about 65mph.I usually get a check engine light. I have had it checked and it says a miss on cylinder 6.I have had the jets cleaned and used shell v power gas and four gas treatments with stp.I don't get a check engine light now but still runs extremely rough beginning at 65mph and smooths out at 70mph but in between that time she feels like she is falling apart .Can you help me?

Reply to
ivan
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Have you checked the ignition? That can be the culprit.

Good information here

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Reply to
Ed Pawlowski

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