OK, so I drove to a wedding a few weeks ago about 3 hours away, and I'm on the highway. I was probably driving too fast anyway, between 80 and 90, but it was so smooth and nice I really didn't notice. Anyway, everything is fine until I think I hear a thumping sound. It sounds like something is wrong with the exhaust, it sounded like a gasser with a hole in the pipe or something like that, going "doosh, doosh" pretty quickly.

I immediately get a feeling I haven't had since the MG days, the oh-$hit, I'm in the middle of nowhere and my car is making strange sounds and I'm on the way to a wedding feeling. I pull over, and the sound goes away after I drop down in speed. I leave it running and get out, and give it a look over. Nothing wrong. I check the trunk to see if anything was loose and rumbling around. Nope. I shrug and go on.

About 90 minutes later, it does it again when I speed up to around 80 something and stay there for a while. Again, I pull over, and detect nothing. Everything is working fine, no overheat, exhaust isn't loose, nothing. I look under the hood and think maybe the tube that runs over the air cleaner is loose and is vibrating against the cleaner cover, so I make sure its secure.

No problems until one brief moment on the way home, but I kept the speed down. I know this is limited information, and is also strange, but has anyone had a similar experience? Was I in the Bermuda triangle? I'll check with my mechanic when I take it in. I drive it every day around town and haven't had any problems since.