How do I add seafoam effectively into my 5.4 intake...? Trying it as a last ditrch for getting rid of the knocking....

 

Well, there's probably more than one way to get it in there but the method that comes to my mind is through the PCV hose. Everything is a pain to get to under the hood. On my '97 it's on the left valve cover standing in front of the vehicle. Just disconnect it and you should feel the vacuum. You may want to trace that vacuum line to be sure it goes in to the intake plenum but I'm pretty sure it does.

I did this to my Taurus and it worked fine. Didn't fix the pinging but didn't hurt it either. Have you tried cleaning your MAF? That may actually help more. Do a search in the Engine forum for it and you'll get a bunch of hits.

BTW I can't respond very quickly as I get very little surfing time these days.

Good Luck!!