One problem related to gas recirculation valve (egr valve) has been reported for the 1997 Chevrolet S10. The most recently reported issues are listed below.
Whenever the air conditioner is being used and the temperature is 90 degrees or above, a loud roaring sound comes from the engine and the truck loses power. It actually sounds like the engine is falling out of the truck. The driver has to floor the truck in order to get it to move. Dealer gave consumer a letter from gm, stating that this was a normal condition for the S10 pickup.