ORIGINAL: Big Block Glock
check your gap in the plug

Stop messing with the new guy....that's just mean. LOL.
"bench" run it to full throttle, watch the tank and fuel lines for bubbles. I have a hunch that vibration is causing fuel foam at high rpm and causing a lean condition.
If it looks like this, you have a problem:
http://s68.photobucket.com/albums/i2...t=MOV03864.mp4