912 ULS with 460 hours built in 2008 1000 RPM drop during Mag test

Sure sounds like a wire issue, butttt I would rule in or out the ignition modules. Is there someone at your location that you might be able to borrow their two modules for a quick test or send yours to Lockwood Aviation in Florida to get tested. A second idea based off your post. If the engine is running and you wiggle you braided wire cable to the trigger coils in different places does anything change? Just a down and dirty quick check.

I can try moving the harness around when its running, thanks.

I did swap the two 6 pin connectors that come from the mag switch, the stator input(red), and the pickups.  I swapped the top one with the bottom one adjacent to the two modules.  The problem stayed with the same switch.  That's why I think that if has to be a problem before the two modules.

Just tried 10 minutes of wiggling the SS braided harness, the exposed lower pickup harness near cyl #4, and lastly the 6-pin plug wire inputs.

All at 2400 rpm.  The rpms never changed and I tried the mag switch while moving the harness in a bunch of different places.  No rpm changes.

Can you remember the two wires that you had accidentally swapped?

Do pickups actually go bad?

Thanks!

Tested some more today.  Same big drop.  The last few times that I started the engine it took a little more to start the engine.  A little throttle and no choke.   AND a few seconds later after it was established a whatever rpm it would just suddenly start running faster and smoother like a switch was thrown.  I think that the problem is getting worse.
I think that I will go ahead and buy that pickup harness.

D