EGR-related performance issues

I've just replaced my EGR valve, cleaned the "S" passage and the intake, and reset the diagnostics. The CEL is gone and the engine idles smooth as new. But whenever I drive up hills, the torque isn't there. I do hear a hearty roar from the engine but no performance - as if the mixture is being altered beyond proper limits.

Again, no CEL.

What needs to be fixed?

Why do we have to guess what year and engine this is??? Also how and what did you do to dtermine the 'fuel mixture is beyond limits" what are the lt and st trim numbers.

OOPS. It's a 2001 base model 3.4L with a well-maintained 152,000 miles on it. Sorry I forgot to re-add that after accidentally losing my message text.

I gathered something was enriching the mixture too much because it ate gas like no tomorrow and performed sluggishly, and ONLY after I replaced the EGR unit.

Only a full scan will tell you anything related to the fuel trims and other sensor inputs, possible contaminated maf also, lots of issues here that require the proper diagnostic techniques. The cat convertors were problematic on these cars and have an extended warranty to 120k I believe, the noise and loss of power you describe could be the issue here.

Thanks for the quick reply. I really hope it isn't the cat, though, because MAFs are easy to clean or pull from a junkyard.

I hate to be the bearer of bad news, but I agree with Max that it sounds like a cat issue to me. GM extended the cat warranty to 120k on the 01-02's due to a known problem, but you're significantly past that.