Er-4: Non-registered data received from meter

Hi Everybody,

I'm a new member, from France.
My name is Matthieu, and I have an WR250R since a year.

Last week I had this problem :
_the engine cut at very low speed (when arrived to a stop for example).
_the engine don't work fine and don't provide all his power
_on a long road at the same speed , the engine cut 'booooooaaaaaaaa' (like if petrol don't come to engine.
_sometimes when want to start she run, sometimes not.

I release my FMF programmer , and put a new spark plug, but no difference.

In diag mode , I have an "Er-4" (not all the times).

Can you help me , please ?

Matthieu