Ouch. Yeah. I've definitely seen this. When exactly did this start? Was it all of a sudden? Had you refueled or done any type of maintenance service right before this happened? How long had you been driving? What was the temp guage reading? What were the weather conditions at the time? When you say the performance went way down, what exactly do you mean? Surging? Cutting out? Stalling? Lack of power? No RPM increase while pressing on gas pedal? More details would help us to give you better "armchair" diagnosis. Just FYI - The late 90's and early 2K's V-6 engines had some catalytic converter issues. Your cat converter may have "gone south" and is causing too much back pressure. Reccommend you take it to a shop and have it looked at unless you're car savvy and have a scanner and an exhaust back pressure tester.