[tccrab]

C4's are especially sensitive to low battery voltage.
If your battery is anywhere near it's expected lifetime, change it out.
Clean & wire brush the battery terminals while you're in there.
You shouldn't have any more troubles, but if you do, the next thing is to track down all the engine & chassis ground connections and clean them up.
(you probably won't have to do this, just change the battery).

Idlers make noise as they age/wear. When it gets noisy enough to bother you, change it out. As I recall, the pulley for our ZR1's is a little different than a LT1 or L98 but they still work.
I'll have to dig through the archives, there was a thread about 6 months ago that detailed the differences and also where to buy them without breaking the bank.

Good Luck!

TomC
'Crabs