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At My Wits End - 2002 RM125 Stutter

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So I'm working on my co-workers 2002 RM125 that he picked up last summer for $500 - down the molehill we go.

He asked me to fix it up on his dime, so I did all the normal stuff to the chassis, new tubes, replaced some spokes, new cables, repacked the silencer...blah blah etc.

Now the problem - The engine has a mean stutter when riding it when it tries to come on the powerband - wont clean out and almost sounds like a misfire. Will clean out an run well when warm on the stand.

Here's what I've done and checked: Nothing has worked. (FSM = factory service manual)

-Head re-cut back to stock specs by Williams Moto Werx
-New piston ring
-Piston has 2~hrs on it
-Cylinder measured in spec (End of spec it has a steel sleeve) on a CMM
-Cleaned PV
-New Boyesen Reeds
-Cleaned carb
-Jetted per FMF spec
-Reset float height per FSM
-New Plug
-Verified PV is functioning
-Re-set PV spring tension per FSM
-New Airfilter
-Brand new FMF Factory Fatty
-Verified Electrical components (Coil, stator, kill switch) with multimeter and FSM

I'm leaning towards a bad CDI box, or maybe slight chance of left side crank seal leak (All thats left to check lol).

Anyone have any insights, sanity check, or a 2001-2007 RM125 CDI box laying around I can borrow to check bikes performance? Or that they want to sell?

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