Spark Plug Boot Dilemma

On my wife's Isuzu Rodeo V6 engine the spark plug boot on 1 of the 6 cylinders is stuck bad on the plug. I've let it soak for a half hour submerged in WD-40 and i've twisted and pulled on it. Well now the top flange of the boot is starting to rip. I am doing this just to replace the spark plugs cause I don't know how long it's been since it was done (not since I've known her) and to add to the mystery the spark plug boot that is stuck is also the only boot that is visually a little bit different then the rest of the boots? The car just needs to last another 1-2 years (2 years hopefully) should I just leave it all together and not replace the plugs or what do I do cause I can't get that boot out?

 

You mean the other 5? Or 6? Thing is I um unsure how to get this boot off. It's the type of engine where it's recessed pretty deep down and it isn't going to come free.