2002, Sonoma, 4WD, Auto, Bad Noise when cruising

Before I end up spending a fortune trying to solve an intermittant problem, that can't be duplicated in the shop, I thought I'd throw it out to the experts. My truck occasionally makes a fairly loud whirring noise when I have been cruising down the road at 45-70 MPH and take my foot off the gas to slow down. The transmission shifts perfectly when accellerating at all times and it is only when I take my foot off the gas and the car starts slowing down that the noise occurs. If I hit the gas pedddle while it is making this noise, the noise will stop. The noise sounds like something is freewheeling underneath the car and when I reapply the gas, whatever it is gets re-engaged. What is going on?

Before I end up spending a fortune trying to solve an intermittant problem, that can't be duplicated in the shop, I thought I'd throw it out to the experts. My truck occasionally makes a fairly loud whirring noise when I have been cruising down the road at 45-70 MPH and take my foot off the gas to slow down. The transmission shifts perfectly when accellerating at all times and it is only when I take my foot off the gas and the car starts slowing down that the noise occurs. If I hit the gas pedddle while it is making this noise, the noise will stop. The noise sounds like something is freewheeling underneath the car and when I reapply the gas, whatever it is gets re-engaged. What is going on?

Sounds like the torque converter

Sounds like the torque converter

I understand why you would think that, but the transmission is shifting perfectly and smoothly. 99% of the time it doesn't even make the whirring noise when I'm slowing down, which is the only time it makes the noise anyways. I can't get it to make the noise on command. It is totally unpredicable at this time.

Had same noise problem.It was the band that holds heat shield on muffler.There are 2. one came off.got extra long hose clamp and it was perfect.Noise was heat shield vibrating on muffler.