125-200cc 2002 wr 250 wont start/stay running

its doesn't seem to be getting a spark at the spark plug but if it does its a low voltage spark, however it will start every now and then, but wont stay runing for long unless i hold the throttle open a little. I actually can still ride it but cant let off the throttle much with out it wanting to die.im thinking it something to do with the electrics but idk. we have cleaned the carb changed the spark plug. drained the gas put new gas/oil mix in . still doing the same thing. please help me guys !

Have the Stator checked.

Spark plug cap, swap it for a non supressed one, also check your ht leads screwed in all the way loose ones if those cause irratic issues.
If the tanks off which i think would make things easy check for pinched wires on rad bolt side and coil side, clean all contacts and go again.

If i remember the stator has low running and a high running coils, should the low running coil has gone bad then a low voltage spark (weak) will cause the problem. (Coil) = the wiring coils in the stator.