Missing at middle of rev range

[Slatter]

Ive raced my off roader 3 times now and ive go an annoying bit of missing about half way through the rev range.
It doesnt happen all the time, generally if i floor the throttle it seem to go straight through it but if you are being carefull and taking it steady building up the revs it starts missing for a bit. Im talkin a few seconds here and only when under quite alot of load. if i go up a gear it goes away.

Ive had new plugs and lead and cap and new fuels filters throughout.
Its a 4.8 JE Engine running on his own chipped ecu, and a purpose built loom. What i find strange is it never used to miss at all when exactly the same setup was in my old racer

Any help would be great,

Thanks

Slatter

[ChrisJC]

Could be leaning out for some unknown reason.......

Chris.

[ian.stewart]

what plug gaps are you running, I had loads of misfire trouble after I opend up my plug gaps reccomended by an after market ignition company

[Slatter]

Erm i just brought the plugs straight from John Eales .....

I just put them in because i never had a problem with them before it will be worth checking though, what gap would u reccomend ??