Leaks Anti-freeze??

sounds to me like its cracked

slick 98, i'm afraid that what ocbaud has said is true. The O.E. manifolds are VERY prone to cracking. the usually break right behind the alternator, but I have seen many come through the dealership cracked at the heater hose fitting on the pass. rear of the manifold, and my own personal 96 GT cracked at the thermo housing. just started leaking from the seal one day. couldn't see a crack and tried 2 new seals before i said F-it and replaced the manifold. there is a way to tell if yours has been replaced. is the part where the thermostat goes into aluminum or plastic? The replacement manifolds are aluminum in the front crossover/thermo housing area. If not, then you need to replace the manifold with the updated aluminum one, otherwise you are taking a chance on it completely rupturing, which it will, and leave you sitting. it's about a 2 hr job to put on and requires nothing but basic hand tools.

PI headswap, or just PI intake with an aluminum crossover for coolant. your intake is cracked.