I've seen the PB blast work wonders when left sit. My buddy had satan-spawn bolts on the lower control arms of his cherokee. After soaking the bolts for three days (two applications per day), we went to remove them they were off and new control arms bolted up in 30 minutes. I would give the plug another spray, let it sit overnight, spray it again in the morning, and use an impact wrench with your firiend's air compressor. You've got the right idea waiting for airtools. sorry to hear its puting up such a fight.