My 2wd sapphire has a misfire when first started, hot or cold, the spec is as follows, long studded 200 block (new), wrc h/gasket, the head has been skimmed and pressure tested, std head and cams, t38, grey injectors, grp a coil, fort motorsport leads, motorcraft AGPS071c plugs, peaks at 30psi, drops back to 28psi,
new engine loom etc. It runs fine when the misfire has cleared and goes really well on boost etc but this misfire's p'ing me off to say the least!
Has any one else had any similar problems or suggestions as to what it may be? What plug gap's would anyone recommend?
Any help appreciated!

 

check for an air leak from inlet manifold

 

hi mate, thanks for the input, already checked for air leaks, engine's done approx 2500 miles and all new cometic gaskets fitted.