I had similar problems with my 96. Perhaps yours have the same cause ?
The overheating turned out to be a broken rubber gasket on the bottom of the radiator cap (even though, of course, its not located on the radiator). Anyways pop the cap, flip it over, and make sure the gasket is not broken or cracked.
The clunking at idle on my car turned out to be a bad upper engine mount. Pop your hood and it should be on the left side above the strut. See if the rubber bushing is still intact.
Hmmm.. another idea on the clunk... Perhaps its the electric clutch engaging on the AC compressor ?
- Rich