Yamaha Fzs 150 Acceleration Problem.

i have Yamaha fzs 150. i found acceleration problem some times.
when i ride 2 or 3 hrs with full acceleration my bike found normal but suddenly gear down and i found my bike acceleration not good and some times thats situation my bike engine off when my acceleration up.
after 5 min wait and again my engine start and found ok.
i already fuel tank clear, spark plug and air filter cleaned, fuel tank cap cleaned, engine valve gap checked. and also ignition coil changed but my problem not solved. some mechanic told me this is my CDI problem. at this situation what should i do...............................