My series 1 keeps stuttering.

Sometimes when i give it some beans and hit the limiter once or twice in second the overboost kill switch comes on. Is there any way to stop this as im running roughly 1bar and ive been told its set to 1bar.

Also, under similar circumstances if the limiter comes on, i think its sticking. Youll drive along and the car will suddenly start to die and pop shit out the back etc. Its ok on overun, and idles a bit lumpy and low and struggles when you rev it, but if you revs the nutrs off it itll clear out. But then when you put the engine under load again it does it.

I took it out on sunday and gave it some proper abuse and then sat around for a bit. After i switch it back on it sat idling for about 20 minutes then just wouldnt drive away. So i left it for 5 minutes, tried again and it wasnt so bad. Then it cleared out and was fine.

Anyone got any ideas?