When you turn the idle/mixture screw in or out with the engine at idle does the RPM go up or down at a steady pace?
If not, you may have developed a vacuum leak. The idle/mixture screw won't do much when you have a vacuum leak.
That’s interesting. When I was messing around with my 235 last night, I was surprised at how little difference the idle mixture screw made.
However, vac gauge was a pretty steady 19-21 inches depending on how I adjusted. Some intermittent, minor needle bounce when I would adjust the timing.
