When the engine is running and I pull the hose off of the PCV valve, the engine sputters and quickly dies. I guess it's getting too much air suddenly going into the intake while at idle. Is this expected? I ask this because I was going to do a Seafoam treatment (first time ever), but the engine immediately dies before I do anything. I aborted the effort until I make certain I know what's going on and what I'm supposed to do. I've read that others say they suck a little bit of Seafoam at a time through the hose, but they are able to never let the engine die. So I assume they pull the hose out of the liquid to prevent the engine from dying? Mine just dies immediately. Is there a problem I should look into or does this just make sense and it's supposed to work that way?

My PCV valve is newly replaced so I don't think that's the problem. It rattled before I installed it.

I need to try it again with removing the PCV valve from the engine and see if I can keep it running by putting a finger over the PCV valve end. I don't understand the direction of airflow normally through the valve - which direction should the PCV valve prevent the air from flowing under normal operating conditions?