toolmaker

Hi guys,
seem to be plagued by a stange mis-fire type problem.
Only happens in first and second when accelerating hard, doesn't do it at all if i'm not really 'trying', or in any other gear.

When it happens its making a banging noise like the pops/bangs on the over-run when decellerating, like fuel igniting in the exhaust.

Car has a full de-cat, Blitz induction kit and a forge VTA. Have tried removing the Blitz and the dump valve but no change.

Just had full service and new HKS iridium plugs.

Any ideas? I'm completely baffled by it!