its been misfiring since i got it but i think its got worse. when the cars in low revs its misfires then once its got higher up the rev range its fine. any ideas? i have an open mushroom filter with no cold air feed. someone said its over fuelling and i need a cold air feed? does this have anything to do with it. it also has a rolla manifold! does this also have any thing to do with it? thankss guys. katy