Cuts out at 4000 RPM's under boost?

[89vanman]

I just finished a fresh rebuild on my van and can't seem to figure out why the thing would cut out at 4000 rpm's at around 15#'s of boost. I have had the thing up to 30#'s with the same cal and basic setup. Some recent changes that I did are +40's, underdrive pulley, larger TO4E 50trim and stage 2 turbine, garret wastegate actuator, and an in frame major. There is no cutout in the calibration and like I say I had the same computer running 30#'s before. Any suggestions would be awesome.

Timing 12 degrees
Fuel pressure 30psi
Autolite 63
180 deg thermostat

[chilort]

Double check all electrical connections, including but not limited to: the multiple grounds to the engine and fuel rail, the coil, and especially the plug wires. The one behind the A/C compressor is easy to think you've got on. The "miss" might not show up until the arching can't happen fast enough (i.e. high rpm).

How bad is the cut out?

I had an issue where mine would just barely, oh I dunno, flutter at 4500rpm, going up hill, and under full post. I switched plugs from Champion RN12YC to a NGK plug for Sea-Doo and have never looked back. The Sea-Doo plug is shrouded considerably. I NEVER thought a plug would make a difference.