S10 Dropping RPM in coast
 

When I'm driving over 80k and take my foot off the accelerator to coast, after about 6-10 secs the RPMs drop right off, like as if I have a govenor and my truck makes a weird sound. As soon as I put my foot back on the accelerator it goes back to normal. I can prevent this from happening if I keep the accelerator or the brake even slightly depressed, but this is hard on my brakes and gas! Can anyone help me out in what is happening?

Welcome to the forum....
If I understand your question correctly, your RPM's are dropping when you let off the gas... this is normal, as the engine is no longer accelerating so the RPM's drop...the torque converter does not ( for the most part) transfer the wheel spin back to the engine so even though you are rolling at highway speeds but not accelerating the engine is mostly at idle

Thanks for the response, but, you didn't fully understand. I realize that when I take my foot off the accelerator, of course the RPMs naturally slowly decline as the vehicle is no longer accelerating. With my truck, if I take my foot off the accelerator on a decline, my RPMs don't just gradually reduce with speed, but they completely drop off...as if my truck has a govenor and it makes a weird sound. If I were to depress the accelerator or the brake, then this doesn't happen.
So, this is not a normal thing and noone I have talked to, including the Chevy dealership has been able to understand or be able to help in any way. But I do know this is not normal.
I am thinking it is either fuel pump, tranny or transfer case related, but I don't know for sure.

How long have you had this vehicle? How long have you had this problem?

This sounds like normal modern day automatic transmissions.

Did you have the transmission fluid changed recently?

Thanks sledge.impy. I have not had the tranny fluid changed recently, but I have had it checked and it's supposedly ok. I have had the truck since 2009. When I took it to the dealership, I tried to explain that the day before this problem started, I had it parked on a steep decline and my fuel gauge indicated empty for over three hours. They thought I wanted my fuel gauge checked, but I didn't, as I do know that slopes create a change in the gauge. My point was that, that was the only thing I could think of that would have been different for my truck and I thought maybe something had been damaged or dry too long or something, as this only seems to happen when I'm coasting downhill, not up... :s