Do you have Arp's in there? They can sometimes be a b***h to pull through. Are you trying to pull the head with the intake and exhaust mani on? That can also feel like she doesn't want to come. You did pull out 10 bolts, yes? Kind of silly, but you never know.

I usually pull them with the intake on, so I suppose I get some leverage from that. Haven't had this problem before but if she really is "undone" then a hard rubber mallet as a dead blow (in a safe spot. Please don't just start wailing away) will help you. If they are arps, then you may need to do some wiggling.

MB