This is kinda hard to explain, but anyway here it goes.

After running for a while, mainly I have noticed it now that it has gotten hot here in the summer. The engine will sound less smooth...it sounds like it is working harder than normal at lower RPM's whereas in the mornings it sounds normal at those same RPM's. I have no idea how to describe the noise, but anyway it only seems to be when the car is warmer.

The temp guage stays in the middle though...I am going to have the thermostat checked to be sure, but do any of you have any other ideas on what it could be?

 

If it is temp related and repeatable it may be the "air to gas" ratio which changes as the car heats up, similar to the choke in the old days. I believe the computer makes the necessary correction bbut I'm not sure of the specifics. Someone else may have more details.

 

Hope those three posts were worth it.