1997 Ford F-150 PLUGS

Heat could be the answer. Try running the engine up to normal operating temperature then unscrew the plug 1 /4 turn. Re-tighten it a bit less than 1 /4 turn and then unscrew it a bit more. Repeat this until the plug is free. There is also plug removal tools, are you using one or just using a regular socket/ratchet. . If the plug is simply too tight or snaps then may have to remove the head and use a helicoil. Once head is out you dril out the stuck plug, tapp a new oversize thread and insert a helicoil to fix.