Ive had another thought.........
I also fitted a new centre console tonight, when i removed it i may have accidentally flicked a high/low boost switch that was fitted to my car previously.
I never use it and have tried flicking it on and off with the car running but it makes no difference.
Maybe because ive now flooded the engine and need to drive it to clear it.
Its very similiar to what would happen if a choke got stuck on?
Could that be what it is and its now over fuelling cos the smell of petrol is VERY strong!!
Cheers for your help guys,
Mark