Just wondering if anyone has any ideas on what to try next! put a mfi turbo lump into my orion last year, a few issue's but ran well- begining of this year the head gasket gave up so replaced the gasket head skim etc and a major service. Before this there was a missfire under boost but i thought it was because of the head gasket. All work has been completed now with new plugs, leads, dizzy cap, rotor arm etc but still has a missfire under boost, on tick over will run fine but at -25psi. when driving it will still be on - boost and misfire badly at 3k then the boost gauge goes to 0 and then dumps like hell! ive checked for leaks etc but not having much luck im thinking its vacuum? any ideas or thought would be highly appreciated

 

Has it been set up as if it hasn't that would be first thing on my agenda mate