i have a 93 cavalier RS 4 door. For about the past year, it has smelled horrible inside. If your not used to riding in the car it will make you gag. Its that bad. My dad and i sprayed a garden hose around the windshied while one of us crawled inside and watched for any water, and low and behold, there is water coming in on both sides of the car. Just wondering if this is a common problem.

It is a common problem of a bad windshield installation by a prior owner, I laughed when you mentioned the smell because it was the reason I got my car so cheap lol. The windshield may seem to be leaking from both sides but actually the leaks are across the top then drips down the sides in most cases, if the car is worth it have the windshield re-installed, if you don't just seal across the top of the windshield with urethane to get by.

Here is the only way to get rid off the raunch.

Rip out the insulation and all

Replace carpet and seats

I currently have the same problem. I ripped out the carpet and found the water coming in with the garden hose technique. I am riding around with no carpet and just the drivers seat installed. I get some weird looks at stop lights
I tried to reseal around the fender seams under the fairing which is under the wiper arms. It slowed it down a little so it may have been slightly leaking from there.
I was wondering how hard it is to pry the windshield out to reseal it, or is it better to pay a windshield guy?
I am too cheap to buy new carpets. I just laid mine out to dry in the sun and sprayed it a bit with lysol to help kill the bacteria that causes the mold. Now its laying in the garage waiting for the leak repair along with all the trim pieces and several ziplock baggies of hardware.