"Larryskydives" wrote in message
...
I had the close to the same thing happen on a 172 with O300A. It turned
out it
was one spark plug lead that was breaking down.

Idle and mag check was good. Static RPM check was was okay. However when
throttle up engine ran rough.

Replaced bad spark plug lead and everything waqs fine.

I have the same problem, and the bad lead runs from a Slick mag to the #2
cylinder bottom plug. Did you replace a Slick lead, or was your mag
another make, like a Bendix? I'd like to know where to find a replacement
lead and how to get it swaged into the distributor cap on the mag end.
Thanks.