Try resetting the TPS. With the ignitiion OFF, press your foot to the floor, then crank the engine for about five seconds (it shouldn't start), then try starting it without the throttle. If it starts when your foot is planted, there is a problem somewhere and I would suggest taking it to a good mechanic to read any fault codes that may exist. Also, as mentioned above, make sure the throttle body and butterfly is nice and clean. Very little amount to carby cleaner on a lint free rag usually gets them spotless pretty quick. Cheers, Ben