If Im not mistaken, the last two plugs you are talking about - (the
bast****) - by the firewall are rough to get to. I believe the plugs were
meant to be changed while a FULL tune up was in place - mainly while the oil
filter was removed so you could reach up from below to access the plugs.
I was able to crack them loose (not literally crack) by using an extension,
a u-joint, a very small extention, and another u-joint so that I could get
the leverage that I needed to break loose.
 My plugs were originally installed right from the factory - I was the first
to remove - so I had sprayed a butt load of WD on a warm (repeat warm - not
hot) engine block before I tried this -
                     I sure hope this helps - and I know its a pain in the
neck - but it worked on this end.....