Right ive been haveing this problem for a few days now, when i floor it and go between 3-4000 rpm the rev counter starts moving up and down and the engine loses power for a second(does it when i change up a gear aswell) sometimes.

its not the MAF cos ive tried that, the cat seems fine, the only thing i can think of is the EGR system, it lost the bit that goes into the exhaust manifold on no4 cylinder and i blocked it off leaving the other 3, would this affect it at all(im planning to disconnect the thing all together anyways)

_________________

best thing i can suggest is remove the rest and see if it still does it for now mate..