Newbie, Coolant issue HELP!

Just bought a 96 Mustang GT a week ago. The car sat for about 4 months before I bought it. When I was buying it the low coolant light was on, so I didn't think anything of it and filled it back up to the fill line in the resevoir. I drove it about 100 miles and it's half an inch to an inch below the fill line already. Is this normal for SN95's? I heard the head gasket might be going if the coolant is dissapearing....I had an 01 GT and never touched the coolant ever and never had an issue with it, but the motor is a little different....so anyway any input would be much appreciated thanks!

The crossover has some wetness around the plenum...its not major but it's there. Like a slight film of stuff but its not a lot. The previous owner put in a new Plunum, throttle body, intake...Im thinking maybe the gasket to the plenum is bad? I just bought this car a week ago and spent every last dime on it so I can't afford to buy anything such as aluminum crossovers....as much as I would love to It's weird cause I used to have an 01 GT and I never had a coolant issue, although I never really checked it either...the motor's are the similar...