how in the **** do you get all these harnesses apart? I got one of the orange ones disconnected, the big fat blue ones I can't get apart, and the grey ones are super*****es

. I had a pair of vice grips, pliers and a flathead on the grey one near the intake tubing and it just wouldn't come apart.
is there something i'm missing? I've wasted 2 hours trying to disconnect a harness