Ok, this little issue is still bugging me... Basically, after the engine's all warmed up, and I'm cruising along, and a slight slope comes in the road, I press the pedal down a little bit (without downshifting), and I hear this gutteral sound from the engine. The sound is very tricky to describe... But it sounds very close to when your exhaust starts to leak. It goes away if I push it to downshift. I know these are EGR conditions, but I replaced the valve and the solenoid, and the tubes are clean, throttle body and intake all nice and clean... Basically no shady parts in here... Everything seems to be running fine, but this noise is bothering me.

I also noticed the same noise when I had my 85 Sedan Deville. It was definitely the same noise, but worse on that thing (drove me mad). Also, on the 85, I noticed the noise would go away after an oil change, but be back within a week. The main bearings were done on that car, so I don't think it's related to that. So my only theory on this is a weakening oil pump? Anyone know?

I am experiencing the same sound with my 94 Deville. I have not done anything yet (except read through several hundred threads).

The noise does not occur until the engine is warmed up. The sound goes away after an oil change but is back in a few days. The noise goes away as long as I have my foot in it during acceleration. Just as soon as the load due to the acceleration starts to decrease (the gas mileage indicator starts climbing and hits about ~20mpg) the noise comes back. When running on flat ground there is no such sound until I need to speed up slowly. A quick speed up does not cause the problem until the car gets close to the desired speed and then the noise comes back.....

Any help here would be most welcomed!!!!!

I found the thread that suggests cleaning out the EGR tubes in the TBI. Do I clean the tubes in place or do I have to remove them? Some details would be great.

Thanks in advance for your help!!

The best way to describe the noise (so it could be reproduced by others) is powerbraking in D and watching the tachometer. My noise (I believe it is spark knock despite all EGR components were replaced) starts at around 1400 RPM when engine is hot (190 plus).