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?

[Fly Boomer]

1 hour ago, M20F said:

Stumped any ideas?

Wasn't this already posted on MooneySpace?

[M20F]

1 hour ago, Fly Boomer said:

Wasn't this already posted on MooneySpace?

Not that I am aware of, found the issue loose nut. 

[EricJ]

31 minutes ago, M20F said:

Not that I am aware of, found the issue loose nut. 

Nicely done.    Was it leaking?

[Fly Boomer]

1 hour ago, M20F said:

Not that I am aware of, found the issue loose nut. 

Good catch on the loose nut.

BTW, you didn't post twice, but MooneySpace is having hiccups today and, when I ask for "next unread post", it sometimes has been serving up a post it already gave me a few minutes ago.  Craig is investigating.

[M20F]

1 hour ago, EricJ said:

Nicely done.    Was it leaking?

No and it was completely by happenstance.  We had run it up a couple times.  Tight EGT spread on all 4 no issues, push above 1800 it went bad.  I am guessing like the 4th run in 3 days when we ramped up cylinder 1 went to 250 EGT almost instantly with the additional throttle.  
 
We checked plugs, wires, compression, bore scope, and injectors.  Putting the injector back on wanted to loosen the spider to make it easier.  We both said did you loosen that?  Tightened it up and put and ran fine. 
 
About 14hrs over 3 days of head banging.  The other nuts were finger tight (they got the wrench).  
 
New problem is the circuit board in the FBO’s gas pump fried, no gas.  Tanks were safe but low when it went in but not feeling like ending a 8 month adventure in a field.  Thus no test flight till I can get some gas in it.  Probably will run out 10 gallons tomorrow and fly it 5 mins to another set of pumps.