chevy s-10

real women drive trucks
i've noticed with my 5speed 2000 chevy s-10 4cylinder that the engine is working overtime. i've also noticed the same problem in 2 fairly new blazers that i've driven. i don't think the rpms are shooting up...it is more of a roaring sound. i'm thinking it is affecting my mpg and haven't gotten it looked at yet.
has anyone experienced this? is it a normal / common thing? not sure but does it have anything to do with the computer?
i'd appreciate any input.
thanks

If it only happens while moving Check the tire pressure, and the tire wear. Often road noise comes from the tire design, and if this is the case you can either live with the noise, or switch to a quieter design. Your local tire store would probably advise you for free.

check the radiator fan clutch if it is stuck you will lose hp and mpg also replace or check the fuel filter if you havent done so already its probably past due

The fan clutch sounds like the culprit. The fan clutch is designed to lockup when the temperature goes above a predetermined level (many different fan clutches for different lockup temps). When a fan clutch does lockup, you will hear the roar of the increased air flow.

If you have never noticed this before, perhaps your fan is going out. Next time you hear the roar, look at the temp guage. If it is high, remember what the temp was. When the roar stops, remember the temp. Now the next time it happens, see if the temps are the same.