Chainsaw Repair

My 036, faithful since I bought it new in 1990, has me scratching my head. I was cutting firewood last week, it was running like new, lots of power and smooth, then it suddenly starts to lose power, chokes, then runs backwards before dying. Never did that before. I could only get it to run again with the flutter valve open (lever in choke position) but also needing choke disc opened 1/4 by hand. In this setting I could close down both H and L carb stems to zero or open 2 turns and little difference.
So, I fully disassembled carb, blew it out, new carb kit. New hose and filter in tank. (Coil I had replaced 6 months ago so haven’t reconsidered that).
After all this it still runs the same, in other words, barely. At least it hasn't tried running in reverse again.
I’m stumped as to what to consider next.
thanks.

First I had to look up 'impulse hose', my old 036 repair manual just calls it 'intake hose', perhaps impulse is a later term? Anyway, the one on it was only a couple years old but did indeed have a pin hole, alas, replacing it still made no difference.
Have also checked boot to engine and tank vent.
It would seem to me to be a useful diagnostic that while it's revving in partial choke mode, I can open 2 turns or completely close both high and low jets and neither affects the rpm's. But What it indicates is over my pay scale,
thanks!

Got it going at last! And am happy to say that your suggestion was correct after all. It was the impulse hose, but not rotted after all these years, merely lost its grip on the crankcase nipple. I had never even heard that this motor has an impulse hose both because it is so hidden behind the carb wall I had never seen it before, and because it is not in the Stihl 034/036 repair manual in the fuel section or diagnostics. I finally found it casually mentioned in a dissasembly section.
So you beat out Sthl corp. in analyzing the problem. The fix was a 95 cent piece of hose.
Me and my trust 036 - we Thankyou!