Idling problems

[trx_rider]

I have a stock 400ex well the engine is stock . most times it idle very good well most of the time but some time it dont want to idle at all and went i press the gas just a little bit it does like the carb his dirty han it hard t say how it do it but the engine dont want to go high rpm but just when i touche the gas .And again its only some times its kind of weird ! could some on tell me with its normal or....??
Thanks!
If you dint undersdant sorry i am french ! :ermm: ask me i wil try again