One of the easiest ways to improve engine and throttle response is by making sure your fuel filter is clean. When you stomp on the gas pedal, it sends a signal for more fuel to go into the engine. To get there, it has to pass through the fuel filter (which filters out impurities and sediment, keeping your engine clean). Asking and engine with a clogged or dirty fuel filter to respond to throttle input is like asking someone to sprint with a muddy towel over their nose and mouth. They can probably do it, but it won't be pretty.
In addition to poor engine response, symptoms of a clogged fuel filter include rough idling, poor fuel economy, trouble starting, sputtering and flat-out stopping. Cleaning a fuel filter is pretty easy, though. Most cars have their filters in the fuel lines between the fuel pump and the injectors. Because they're made to be cleaned and replaced (if they're really dirty), it's fairly easy to pull a fuel filter from your car's engine. You can clean it by blowing some compressed air on it until air flows through it freely. But if you can't get air to flow through it, it's time for a replacement. Put your dirty fuel filter back in for one last trip to the auto parts store. Playing taps as you throw it away is optional.