I have had this problem a while. But now it's starts to annoy me. When I accelerate with full throttle, it sounds like its going to choke, but it wont. With full throttle it goes 80km/h(49mph) max. Engine runs smoothly so I dont think that there is any problem with the spark. With 3/4 thorttle it goes with full power smoothly but is hard to get that right spot. it could be petrol filter but dont know because with the right throttle you will get full power (90% of time Im driving all by my self so dont know what happens with bigger load). The point is that everything is normal works like normal but hard to accelerate fast.