Hi,

My 1996 Rodeo (V6) makes a noise that can be described as fluttering or
air compressor or diesel engine like!  It has 146K miles.  Last time
the timing belt was changed was at 75K.  Just had a tune up and so the
spark plugs, fuel filter, air filter, PCV valve are all new.  Fluids
and oil are all at normal levels.

When I start the car in the morning, it sounds like an air compressor
starting up.  After driving around for a bit, it quiets down a bit.
When stopped and idling, it sounds like diesel engine and has a
fluttering noise to it.  The funny part is that I filled it with 93
octane gas and the noise seemed to go away for a few days but it's back
now (even with the 93 octane).  I live in Boston so it's pretty cold
when I crank it in the mornings.

Any ideas what might be going on?  The mechanic suspected that it might
be bad valve covers and that replacing them is not cheap.  Would
changing the timing belt solve the problem

Thanks for any ideas.

Rgds,
BC.