Take a look at TSB 07-028: Pinging, Rattling, or Squealing During Light Acceleration
SYMPTOM
While driving under light acceleration, you hear an intermittent pinging, rattling, or squealing from the engine compartment. The noise can easily be mistaken
for an engine ping or spark knock. In some cases, the noise happens only during engine warm up.
PROBABLE CAUSE
The intermediate shaft heat shield is loose in its mounting bushings.