Whirrling Noise.. gas mileage

[skistorm]

Hi,I have a 2004 Base with 137k miles. It has been about trouble free. I changed a belt tensioner at 50k miles and an 02 sensor maybe about 5k miles ago, but thats about it other than routine maintenance (plugs, tranny fluid and oil). Lately I have been noticing a pretty quiet whirrling noise that comes on occasionally at highway speeds no matter which way I turn. Also I seem to have been getting much lower gas mileage and the car does feel a little sluggish. I have gone about 160 miles (nearly all interstate) and my tank is half used. I am not sure if the two problems are related, but I was going to dig into it a little this weekend. Any ideas of what I should check?FYI, I did Seafoam maybe about 1500 miles ago.. the kind you spray directly into the throttle body. Thanks for any help!

[circuitsmith]

Change the thermostat.Clean the MAF sensor.

[skistorm]

Thanks. Looks like it was the MAF. I cleaned it previously but I didn't realize I was only getting what I think is a temperature bulb, not the diodes deep in the assembly. It seems like power and gas mileage is coming back. Does it make sense to pull the battery to reset the computer? Thanks again.