Hi Matt,

Check for vacuum leaks.  A loose or cracked vacuum hose can
suddenly give you a high idle and burn things (valves) up due to
an overly lean mixture.

Chirping is often combustion gases under pressure escaping.  The
last time I had that problem in my '72 bus, it was a leaking
head gasket that apparently only leaked when the engine was
cold.  (My theory is that my normally really good Seattle
mechanic had a bad day when torquing down the new heads.  Either
that or I must have really overheated it on a drive from Seattle
to the Bay Area.)  The Mexican mechanics stuck a new gasket in
for that cylinder, telling me not to worry about the slight head
erosion from hot escaping gases--so far (10K miles), they seem
to be right.  It's not like there were a bunch of rebuildable
1700 heads to be found there in Guadalajara, either.

The time before that (in 1984), it was a spark plug that
vibrated loose on the Pennsylvania Turnpike.  I thought for sure
my trip was over on the spot because it sounded like all hell
had broken loose.  Instead, I coasted off the road, cautiously
restarted (stuck my fingers in my ears as I peered into the
engine compartment--ooh that was loud!), figured out what had
gone wrong, screwed the sucker back in, and drove another 10,000
miles.  I still probably undertighten rather than overtighten my
spark plugs because screwing a plug back in is a lot easier than
inserting a heli-coil into a stripped head.

Your chirping could just be a cracked heater box, too.  Don't
poison yourself with Cabon Monoxide!

Good Luck!
Dennis