weird rm250 problem

[chris642]

im having a little problem with my 97 RM 250. its nothing serious, just something weird i want to get rid of. when im riding it, sometimes it will ping like it is about to run out of gas, this is only when im decelerating. and it pings like this when i come to a stop and let it idle. it is weird that this ONLY happens when im in a trail or out riding, when im warming it up it idles perfectly and when i come back from riding, get a drink and cool off for a half hour, it runs and idles perfect. I have never been having this problem before i let it sit for like 2 weeks with the gas on, im thinking it could possibly be some junk in the carb, but it doesnt explain why its fine when im warming it up and when i let it sit for a little. do you think it is not getting gas, thats why it only happens when im ridding? its not the sparkplug, i changed it a couple times and it is always the same. I just want to hear some of your opinions!! thanks!!