ive had this problem many times before, usually fixed for a few months with a new lambda sensor
recently i fitted one, and the problem came back in about 2 weeks
now, ive recently changed where i buy my fuel, and the problem has gone, the only other thing thats changed is that ive started to put the clutch in when i start the car, but i cant see that being related really....
always used V-Power, so its the same fuel just from a different, busier, Shell
if anyone else gets that first 30 seconds of the car holding back, try a different petrol station and see how you go