I recently installed new cylinder head on my 1996 ford crown victoria along with all the right gaskets and everything but now the car oil is a milky grey color and the spark plug wires will pop out

I think you did not torque the head in the right order and/or tightness. The gasket is blown! Replace it. I don't understand what you mean when you say the plug wires pop out so I can't help you with that right now.

Milky grey oil means water or some other liquid like antifreeze in the oil. Head Gasket! Oil pan needs to be drained and removed, change the gasket, oil and check seals leading to and from for leaks. Sometimes a motor sits for a while and gaskets dry out, they need compression to seal. Plug wires popping off - they are either not the right ones or they are not pushed onto the plug well enough.Plug wires come in different sizes.The plug wires should make a popping noise when removing from the plug. Check to see if the motor is blown by doing a compression check. Leaving condensing liquids in the pan can cause rust and further problems to the motor thus some urgency to cleaning the pan out. Any metal flakes and there could be further motor damage. If it turns over you might be lucky! Clean it out before attempting to start it and ensure battery is disconnected, eye protection is used. Hope this helps!