miss side A only above 5000 RPM

Start by checking the simplest/cheapest - spark plug caps/leads & the plugs themselves. 

Look for loose cap, plug fouling/damaged electrodes. Move on to lead damage, continuity/resistance.

Hi Walt

On a ULS you can do a quick troubleshooting by removing the connector plug from the A module and switch it to the B.  If the problem moves with the connector then you are not chasing a problem with the module. 

Cheers

Sean, that is what I was thinking. The wires and caps are new within 50 hours. Of course that doesn’t mean anything. I have a hunch it’s a plug that is fouling at the high rpm/load. I was trying to think of a matrix to narrow down if it is spark plug related without changing all. My thought is to swap the plugs front to back on the tops and bottoms. If the miss changes mags then it is a plug issue. 

"The wires and caps are new within 50 hours. "

Double check your workmanship. A bad connection in the HT system can result in a spark jump at lower rpm, that fails at higher ,causing a miss.

today I swapped the top plugs front to back, an easy test without removing the lower cowl. If one of the plugs was a problem the miss should have moved to the B ignition. The test flight both sides worked perfectly for the first 5 minutes then the same A started missing. So not the top plugs. 
Off with the bottom down and get more serious. I pulled the bottom plugs, they looked good. In the process looking at the wires, see pic. Every plug wire was, melted where it goes into the cap. These wires are questionable. I bought bulk 7mm wire from Spruce when I replaced these 50 hours ago, it seems the insulation can’t handle the temperature. What wire is good for this engine? I cut back all wires and will test tomorrow. Even if it is not missing I think I need to find a more suitable wire.