You have to break it in you know, right. If you have it set rich for break in, it should definetly have a slow throttle response. You should run about 2 tanks through before you put it in the air, so it is reliable. My .46fx is the smoothest idling, most reliable engine I have. The only deadstick's I've ever had was when it ran out of fuel, and 2 on the first 5 flights.