2003 Ford Mustang Slow acceleration

You know we can't tell that over a computer, but worn spark plugs are a logical guess, especially at the mileage you listed if they haven't been replaced yet. I'd start with replacing them and the wires if your engine has them. When you have an engine-related problem, you have to list which engine you have. One misfiring cylinder on a V-8 engine won't cause as much of a problem as one misfiring on a four-cylinder engine.

You also have to consider a plugged exhaust system, worn camshaft lobe, failed injector, and low compression. If spark plugs don't solve the problem, you'll need to have the cause of the misfire diagnosed.