You may need a new Turbo. It happened on my Ford Mondeo Zetec in 2005. There was an immense lag, I couldn't get it going over 5mph until about 2500-3000 revs. You should take your car to a local mechanic, or a main dealer if its fairly new. You should start the car up in second gear, don't use first unless its absolutely necessary, this will save fuel temporarily.
David Arnold
February 2010
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