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