theres only one thing i can think of that might be the problem.....do you clear the pipe after u hit it?

if you dont know what im talking about.....there should be a small hole on the outside of your pipe next to the bowl. when you are hitting the pipe, cover up that hole. when you are nearing the end of your hit, let go of the hole and suck in all the smoke that is inside the pipe. if you leave smoke in there, it gets REALLY nasty tasing REALLY fast.