I'd say double check for vac leaks,spray some aerostart around manifold and see if it's sucking air anywhere. If it's a cut and shut like mine it could be cracked around the welds.
I also had to take the breather between rocker cover and manifold off cause when they modded the fwd manifold it is open and is a massive air leak,caused mine to idle really high.
Luckily apart from the first motor i put in havin dodgy rings mines been ok. just had oil leaks. dizzy still leakin,can't get a seal locally.
I've got a spare computer,map sensor and coil/ignitor if ya get really stuck. Shame i'm too far away to help.