Welcome! Read, read, and read some more, my friend! Do lots of research before tearing into anything. The best places to read? Here, in the Cabriolet forum is good. Also the Golf/Jetta III forums, as they share all the same basic mechanicals as your Cabrio. Finally, and one of the best places to read, is to get yourself a repair manual from Bentley publishers that covers your '98 Cabrio. This repair manual will walk you through most basic trouble shooting and repair procedures on your car.