2001 Z24 7o,000 Miles, I have this rough idle not really rough but not smooth... I just went through two weeks of -45*c weather... anyways.. when you slowly raise the idle to 2700 to 31oo RPM< in neutral, you get this slight vibration like something is off balance. Could this just be a weak plug ( still on GM plugs. replaced at 60,000_) or another coil pack. Has anyone had ignition problems with those spark cover sleeves? I also get a light growl when de-accelerating from anything higher than 3100 RPM like running 2nd or thrd to 6000 and letting off I get this *buzzzing from the filler cap area. then after you cross 3100 rpm, it disappers.
HELP i'm off warranty in 6 weeks.

well you are not supposed to raise the RPMs that high in neutral. thats just asking for trouble



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