i have a 2002 cougar and the transmission slips what could it be?????

Hello, sorry to hear your problem. I know how frustrating it can be. I'm guessing it has an automatic transmission. First, I would check the transmission fluid when the vehicle is warmed up to operating temperature. It should be in the hot range or below a little. If you can see fluid on the stick you should be okay there. If the fluid is overfull that is just as bad as not having enough fluid in it, "so do not overfill." Second, If the transmission fluid is okay I would check to see if there is any codes the computer is storing. Any parts place like Autozone or O'reily's Auto should have a code tester they can hook up to your computer on your car to test for codes. Those are the two things I would start with other then taking it to a transmission shop. Good luck.