1992vw cabriolet Just replaced engine when car is cold and you attempt to accelerate the car has a combination of hesitation and sputtering any suggestions?

You may have a broken or disconnected vaccuum line probably at or around the fuel injector or fuel line its most likely caused by a vacuum leak also if its injection check the cold start valve is working on the injection if its carb check the choke butterfly is closing and the choke idle speed is high enough could also have pulled a bit of dirt from the fuel tank but i wudda thought this would have affected the performance when hot too