The coolant overflow cap could be at fault too allowing excessive pressure to build but I agree its probably the intake itself leaking. I suggest trying the pressure test again and try to pinpoint the leak better. These intakes like to form hairline cracks in them so you might as well check to see if that is what it really is before buying a new intake.
07 Gt Tungsten Grey
Roush (Airaid) Cai, GT500 Tb with BlowByRacing Adaptor Plate, UPR O/r X Pipe, M80's, Pypes Muffler Delete Axle Back, Sr Performance Adjustable Motor Mounts and Steeda Tri Ax Short Throw Shifter
02 Gt Mineral Grey
Steeda Sport Springs, 3.73s, Pro5.0 Short Shifter, Pypes O/r X Pipe, full 2.5 inch exhaust with M80's, 75mm Tb and C&L Plenum
87 Mercury Grand Marquis