I have a older 61 husky, and overall it works great, but lately sometimes while I'm cutting wood the saw will bog or start to die out. Blip the throttle and it may get better or the saw may shut off. You then may have too start it 6 or 8 time before it will finally pick up and run normally again, then 15 or 20 minutes later it happens again. Any ideas on what my trouble may be?