I have on what seems a permanent loan a Jonsered saw with an 18" bar that up until recently has performed great for me. For the last week or so I've been working on a large oak tree. This has required more "all out" running of the saw than what I have done in the past. After about a tank of fuel it's hard to get it started again and does not seem to run well. Someitmes I cannot get it started unless I leave it sit for about 15 minutes or so and even then if it stalls it won't start again for awhile. The only thing I've done differently recently is adding Star Tron enzyme treatment to the gas...is this by chance the culprit or is something else going on here?