7k stutter?

[fatfreddy]

I had my 4L1 (with 370 Fahron conversion, Zeel ingnition and Mutt’s mid range pipes) set up on the dyno in February and it ran a treat and, for the most part, still does. However, it has developed a stutter at around 7k in the higher gears. Any ideas what might be causing this?

[stasky]

if it was set up on the dyno,and ran fine i would say shit fuel

[rigga]

Are you trying to pull through the rev range in too high a gear?