Like I said before the chimney is clean so It is not coming from that.
I can not use a damper in the pipe according to US Stove co. They told me to put in a barometric damper.
Any other suggestions?
Ignore what us stove told you, most stove manufacturers will tell you not to put in a key damper but in the real world they are necessary in installations with chimneys taller than 20ft. A barometric damper is not what you need.