Hi, recently aquired an 87 XR3i and it was running smoothly until it stalled once during idle. After that it wouldt run for longer then 20-30sec, starts like a charm everytime. Now it is only during idle it stalls, if I give it some throttle it doesn’t stall but if i let it drop back down to idle rpms it stall. Wondering what could case this? Thank you for any tips.