Yfa carb stumbles on deceleration

Just helped my buddy rebuild his carburetor on his 73 250ci maverick. We ended up combining 2 different carburetor to put a vacuum choke on it and now it stumbles on deceleration. It stops doing it when you blip the throttle. I'm younger guy so please explain as best you can.

 

Vacuum Choke ? - try to post pics' would help a lot ...
.
sure is open ended as far as basic problem described of 'stumbles on deceleration'. .
first, are you sure it's YF carb ?. ' Thought all 250's used RBS carbs and 200's used YF's ...
.
check ignition timing and vac' line to distrib' before F'%^& anything further .. .
.
have fun
.
RBS - YF'
.

 

Thanks ill check this weekend and update

 

Never-ending just checked it's a yf

 

"Nevermind"

 

I have never seen a vacuum operated choke on a factory carb (or any carb for that matter). One needs to "blip" the carb to get it off the choke setting once it is warmed up a little.

 

Is there a heat tube from the exhaust manifold to the choke that maybe someone decided to connect to a vacuum line?