to me that sounds like something is obstructing the air intake. Look through the air intake regulator, if you see something obvious like soot, debris, spider eggs, etc. clean it out. If you don't see anything, clean it out anyway, you can use an air compressor. Stick it in the air intake and blow. You could also use a garden hose for this, but you'd have to dump the water out and let it dry before using it.