Hello,
I replaced the thermostat in my 2000 3.1L Grand Prix SE yesterday. I had to remove the throttle body to get access to it. After putting it all back together, my car now idles around 3000rpm in Park or Neutral. It drops to around 2k when driving which is still a little high. I can definitely feel it taking off faster and it seems to buck a little bit here and there while driving. I did hear a loud hissing sound when I first started it up right around the throttle body area. I don't hear the hissing sound anymore, though. It justs sounds like it's running a lot harder. So my question is, would a leak around the throttle body (I did not use a new gasket and it's possible that the gasket wasn't properly seated) cause these symptoms? On the plus side, my car seemed to heat up super fast!
Thanks guys!