Could there be problems accelerating after new crankshaft sensor fitted?
It could be a dirty up throttle plate but most likely they screwed up the crank sensor, take it back to the place you had it serviced, tell them to make it right, if they give you any crap treaten to call The Buereau of Automotive Repair, (This will strike the fear of God into any sensible mechanic) they will most likely fix it at no charge to you at this point, and if not then DO call the Buereau they are in the government listings in your phone book, this agency employs agents who are experianced former mechanics, tell them your touble and they will investigate it
