I recently got a stihl 051 AV from my great uncle and the saw will crank up and run like a dream for a little bit until it gets good and hot then it will bog down and cut off. You can wait a while to let it cool off and it will crank right back up no problem and do the same thing, run great till it gets hot. I was able to find an ignition coil to replace the original one but that has not fixed the issue. Any thoughts on what else may be the problem?