Was just about to ask this, been out in the car tonight......it drives fine if you take it easy up to whatever speed and cruise at 80 and so on but as soon as you put your foot down a bit faster it as you say misfires and kangaroo's.....sounds like your exhaust is blowing loads at the back. try get in in tuesday after work.

coilpack

underload, weak coil=weak spark=misfire

£25 fix/coilpack
 
Cars Fixed now, ended up been a brand new ngk platinum spark plug that some how cracked and burnt slightly on the white bit-dodgy plug.
 
iv been having this problem under full load it bangs and miss fires but then fine normaly but i have just fitted brand new IK22 plugs and 4 brand new bolt down coil packs and still having same problem. did a quick log and seeing no cf's any one idea what else could cause this problem?