I don't know how other mechanics sort things out in their head and approach problems like this. What I do is make an initial guess, look at that and if I'm right I fix it. If I'm wrong I start from the beginning and kinda follow a flow chart in my head till I come up with an answer. This system has worked pretty well. When I'm right it saves a lot of time and money. When I'm wrong I only lose the couple of minutes it took to check out my initial guess. Either way I'm always looking out for other potential problems with the equipment as I'm handling it.
My guess on this saw was a loose carb or damaged intake boot. When I pulled the top cover I discovered the carb was in fact loose. No carb boot on this one. Hey, I don't know the inside of every piece of crap chainsaw ever made.
The top right intake bolt is broken. The stud is in the cylinder and won't back out with a pick. I was thinking about drilling the stud and using an easy-out. That can be a pain so Al suggested just welding a nut to the stud and wrenching it out.