1996 Ford Mustang

Are you trying to take out the nipple or remove the hose. Either way there is no special tool. Just a pair of needle nose pliers. Are you talking about a spring clamp?

Its hard without looking at it but im almost positive you can use a pair of needle nose pliers and push in the 2 plastic retainers and the connector pops off. You are problably having problems because its corroded. Are you replacing the hose? If you are then you can just yank it off. If you need to reuse it then you will have to be gingerly. Any possible way for you to snap a picture of it and upload it. So I can give you a more accurate way of removing it.

Is that going into the plastic manifold? If it is then its not removable, it comes free with a new intake manifold. These engines change so fast its hard for us to know exactly what you are doing. The plastic intake manifolds are having problems with cracking but usually its up by the thermostat housing. They have since updated the design to eliminate the cracking. I have replaced this intake manifold a hundred times for leaking. Dorman is a aftermarket company that sells the updated intake manifold, compare their price with fords. Although ford manifold has come way down in price too. Hope this helps