My boss has an o1 Tahoe with a power problem. Awhile back it started making a loud grinding/howling noise. Sounded like it was coming from the trans area. After awhile it quit making the noise, but when he puts it in drive it pulls down almost to stall rpms. Has a loss of power too. Let off the brake and it takes off, but still doesn't run right. He was sure it was trans or torque converter. Took it to a trans shop and they went thru it and said there's nothing wrong that they could find. Any ideas? Thanks

Any check engine lights on? How many miles on it? It might need a new fuel filter, plugs and wires? Maybe dirty injectors or a bad fuel pump? Was the grinding noise more like a whining sound? could be the fuel pump going bad??? Just a few guesses to think about.

He says it was more like a knocking sound coming from the area of the trans or torque converter area, that gradually went away. The rig still runs, but with loss of power.

Any other ideas?