Vauxhall Astra poor acceleration / excessive fuel consumption

Car will start first time, but when cold will die down and cut out immediately. Need to rev excessively to prevent it from cutting out, wont cut out when engine warms up. Moving away, very slow and needs high revs to start moving, always need 1st gear for inclines even then it struggles at 5mph. Runs really sluggish at all speeds, can barely get it over 40mph. Using double the amount of fuel, and very strong smell of fuel in car. Have had new vacuum pipe fitted (perished) but not solved the problem.