Yup, it's most likely the vents. My passenger side vent was only half connected and missing half of the seal.
I grabbed the seal from my parts car and clipped the vent back on tight. So far no leaks. I will be taking off the bumper though to apply my own sealant to keep out water 100%.
My 2000 leaks even though the seal and vent is locked tight. I just have to pour a glass of water down the outter edge of the trunk, and it drips down onto the vent and leaks a little from the top. I guess that bumper is coming off too.