Thanks for the suggestion, but unfortunately I've tried that - truss
in this case is attaching post whatever it's blocking on (so I just
see it sleeping), and I haven't yet waited out the problem to see what
happens when/if whatever's blocking times out. Any other ideas?
truss reports nothing? Not that it's waiting in a blocking operation? On the systems I'm familiar with at least, that means it's not waiting for I/O, but is off doing something else. That would indicate it's not waiting for a proxy response or a user request, but something else altogether. I'm not sure what your system is, so its truss may behave differently, you could do some quick experiments if you're not sure either.
The suggestion to take a look in a debugger is a good one if your Apache has debugging symbols. That may be a good next step.
Good luck!
-----Scott.
