I have developed a miss above the staging point.  The fuel pressure seems ok, the mixture also seems ok.  I am at a loss.

 

To try and troubleshoot, I am considering getting above the staging point and disabling the primaries and secondaries to see if I can identify which is the cause.  Since it runs ok below the stage, I assume it is not the primaries.

 

I recently changed my fuel filters and installed a large canister filter.  There seems a possibility  that I introduced some contamination that clogged an injector.  Other wise it seems it must be spark related.  This just happened one flight ago.  The engine was running fine, till that last takeoff.  It was missing and would only get about 6300 rpm.  After take off, I turned the prop back and slowed the engine down to below that number and it smoothed out and ran fine the res of the flight.  Today while taxiing around, I noticed that the miss was back.

 

Opinions welcomed.

 

Bill B