missfire and loss of power

[Tony100]

when i put a new head on my g40 (gt head) i havent driven it in a few months toook it out earlier the car has devolped a missfire like its running on 3 cylinders? i havent changed anything besides the relvaent gaskets ??

its also had a serious loss of power aswell?

[Tony100]

no one??

[PeteG40]

have you done a compression test? to see that the head gasket  is still sealing?

have you checked the rotor arm/dizzy cap for damp etc?