1998 Ford Mustang what is this strange liquid

Engine Performance problem
1998 Ford Mustang 6 cyl Two Wheel Drive Automatic

there is a strange yellow mustard colored I guess you can call it a liquid coming from the engine to the cars air breather. I have no idea what this is for I have never come across it before. It has just the faintest hint of coolant but why on earth would it be coming from the engine to the air filter? It almost has an oily consistancey but its watery at the same time. What is this where is it coming from and how do I fix it