IO-360 rough above 2200

[M20F]

Overhaul back in.  Starts perfectly.  Mag drops at 1700 perfectly.  Prop cycles 1700 perfectly.  EGT/CHT spread is normal.  Runs and idles smoothly up to a bit past 1800.  As in perfectly. 
 
Crank @1900-2200 starts to pop, runs rough, on either mag.  Manifold at 27” and 2200 rpm (max rpm) is 13.8’ish, fuel pressure is good.  Boost pump on or off no change.  Switch mags no change.   Mixture leaner makes it worse.  Getting some gas on bottom 1 and 4 plugs.  
 
Plugs (finewire) cleaned and tested.  Mags timed correctly and have about 100hrs.  
 
Stumped any ideas?

[Rick Junkin]

I'm no expert but sounds like a fuel delivery/distribution issue. Perhaps something got into the fuel injection system during assembly or installation?

What do the EGTs look like when it starts running rough? That might point you to which injectors to look at. It sounds like you have at least one cylinder running leaner than the rest.

Cheers,
Junkman

[PT20J]

Popping can be a sign of a mixture problem. First check the mixture cable rigging and injector nozzles since that is easy. Also check for a restriction in the air intake ducting. Was the servo overhauled along with the engine and did the overhauler run the engine in with this servo on a test stand? This would mean that it ran OK after overhaul and it has something to do with the installation. Do your have an engine monitor? If so, look at the EGTs to see if it is one particular cylinder.

[Shadrach]

This happened to a hangar neighbor with a fast back 182.  It turned out his governor was improperly installed causing the prop to go full course when the throttle was advanced. The engine would not rev higher than about 2000rpm and would go into mild detonation if held there.

[M20F]

It is in other thread but a nut got loose on the spider.  Wasn’t leaking gas but was sucking air.  Tightened it (and the others up) and runs like a champ.