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