1999 Turbo S when cold

Hi All,

I have an Auto 1999 Turbo S.  Occasionally when i put my foot down(When cold) it seems to do nothing.  It doesnt misfire, just feels incredibly flat and wont rev or change down.  If i change down using the box it comes on boost and goes OK but the engine check light comes on.  It sometime goes off very quickly after and then runs fine.  It only seems to do this when cold.  Is this a fuelling issue, could it be a split hose?  But as said once on boost seems fine so the split hose doesnt make sense.  Any suggestions would be greatly appreciated.

Many thanks

Dan