Shake and shimmy

My 72 mercury has a problem when you accelerate the car kind of shakes and spits and sputters. It seems to only happen when the engine is warm. The only thing I have changed recently was to set the timing due to her being hard to start especially if I let it sit a few days. I did notice that the vaccum canister is loose on the side of the distributor. Looks as if the molded mount part of the can where it joins the cap is split almost halfway across. Could that be the culprit? regards,

tdubb