Accelerator not responsive on the bajaj wave

Hi
i own a 2005 bajaj wave scooter. ive been facing this problem of non responsiveness from quite some time. the thing is that there is a time lag of almost 3secs between my turning the throttle and the scooter accelerating. lately the engine keeps turning off if i dont keep my hand on the throttle. i have to constantly keep the throttle twisted to keep the engine on. moreover sudden twists of the throttle,as we do at road junctions, and the engine konks off in the middle of the road. one of my friends told me that there is some adjustment screw in the carburator which has to be fine tuned to get the desired performance. i even opened the entire engine section but was unable to find the carburator. pls help!!