Hi Alan,

Canister? do you mean the oil trap?
Did you clean the EGR valve and it's port to the intake manifold?
(Mine was completely plugged here)
The little tubing from the flame trap to the vacuun tree was plugged too.
Leaving that plugged builds up too much engine pressure, then you can
blow out oil seals for a nasty adventure.

Everyone suggests: "Throw away that flame trap"

Check all your vacuum lines and fittings for 1. leaks or unhooked
and 2. for being plugged and 3. for being soft and mushy and able to collapse under vacuum (this being the same as plugged)

Good luck, Bill