Will the tube seals work on aluminum heads ?

Now I changed the plugs and left the washers on. Drove the car and the smoke and sputtering cleared up as usual but now when it sits for a while and I start it..it fires up nicely but idles erraticly and smokes for a few minutes..like I just changed a plug. So I "assume" there is a tube or two leaking into a cylinder or two. New tubes and no washers ?