GY6 w/mods sputters. Need help figuring out what's up.
 

My Kandi 150-FS was getting really hard to start and keep running. Found that the valves were tight and were starting to wear the cam away. Ended up rebuilding the top end. Before the rebuild, it would struggle to do 25mph. Now it'll do over 30, I'm sure it can hit 35 with enough road. However, when I get to the end of the road and turn around, it'll sputter like it's running out of gas. Sometimes, it'll die. If I wait a minute, it'll start back up, sputter for a few seconds, then run 30+mph again, then at the other end of the road, sputter again. I'm just a couple hundred feet above sea level for the record.

Here are my mods:
155cc "big" bore kit
New head
A11 cam
BDX exhaust w/baffle still installed
"Performance" coil
Scrappydog intake w/Uni filter
Keihin (Japan) carb w/35 pilot & 126 main
Mikuni fuel pump
39 tooth sprocket
10.5 gram sliders
1500RPM Yellow spring
Larger driven face
New clutch

I've also replaced/installed/checked:
New petcock
Fuel lines
Fuel filter
Verified no vacuum leaks
Fresh spark plug
Checked the wiring, no frayed, broken or loose wires

I have two carbs, one Japanese Keihin (old but clean) and one Chinese PD24J (Brand new). The Keihin is the 35/125 jets and the China carb is 35/135 jets. The sputter happens with both carbs. Pilots and fuel bowls in both carbs are clean. I have transparent fuel lines, so I can see fuel is getting into the carb. I have a "performance" adjustable CDI (DC) and it'll start up, but sputter and die within a few seconds, regardless if the engine is cold or hot. The sputter is almost exactly what it does while driving. Swap in the stock CDI and it'll run like described. I've tried a couple different coils, no change. I feel like I've narrowed it down to it being a CDI issue, but I don't have a spare CDI to test other than the stock and "performance" one I have. I'm kind of tired of throwing money at this thing to hope that it works.

Any ideas?