I've read lots about possible bottom pulpy woodruff key being worn is this a common thing? Also how do you sort it do you have to buy a new bottom pulley? Are they easy to get?

I'd agree with Brett and dav and get the codes read. It's likely to be the crank sensor or wear on the bottom pulley woodruff key that's throwing the crank timing signal out of sync.

[Edited on 15-04-2015 by mattievRS]

As Brett says get codes read, you can use the paperclip trick.

Also sounds like it could be a crank sensor

Have you checked if there's any fault codes?

Hello I have a corsa b Sri 1,4 16v x14xe started to get a misfire so a changed coil pack ht leads & plugs along with a oil & filter change car ran sweet for 2 days now when it's hot it's dropping revs losing power & cutting out will sometimes start first turn and drive for 2 min then happen again other times will take a while to start again ! Av changed the head temp sensor but has made no difference dose anyone have any ideas of what a could try next or has anyone had same problems before thanks for any help :) if your gonna be a knob please don't comment haha