This summer I installed a new Pertronix "Flame Thrower" dizzy with pertronix pick up and their recommended coil. Since I have sorted out the AFM I have attempted to dial the idle down to 950 RPM. At that speed I get intermittent spark drop outs evidenced by tach needle dropping along with engine stumbles and the occasional stall. When I throw on the timing light it is obvious that there are missing spark events. The dizzy shaft has side play. There is no way to reduce the gap which would probably help the situation. I have been in contact with Pertronix and they have sent some items to check which made no difference as they did not address the root cause which is probably shaft run out and uncontrolled gap. Has anyone had this a similar experience?

I have recently had a generic copy "Pertronix's" that idled properly but failed under light load causing the spark condition you have,folks say these units work or they don't but in this case the module must be faulty.
I fitted points and the issue went away,I would guess you if you can change back to points you would get similar results if every other part of your ignition is up to scratch.
What leads are you using? if solid core you will have issues ,the Ignitor 1 unit for example is the only one that will work with solid core copper leads.
The "air gap'' for ignitor 2 is 0.010 up to 0.050'' so there is a fairly wide range.
I'am a fan of the Clewitt shielded leads ,very well made and work very well for a fair price,good luck.

Thanks for your reply. It is the ignitor III and I am using the recommended resistive BERU plug wires. The adapter plate that is provided has a bevel head screw which makes it impossible to change the gap. I think a contributing factor is the sloppy bearing in the dizzy they supplied. I am hoping that they will replace the set up with a new one that works at idle.

So do you think the air gap is exceeding the maximum ? .

Either that or the ignitor is bad. Pertronix has agreed to send a warranty replacement. I had to send them a picture of the old one destroyed (wire cut off at the unit). We'll see if the new one works better. Thanks.

So I installed the warranty replacement Ingniter III and all is good. Thank you Pertronix.