I would also say a clogged cat, because I had the same issue when I had my 03 Monte and it sounds similar to what your saying. I never got a CEL either. Although, when I had my issue with this, yes the car felt like it had absolutely no power in the mid to upper rpm range, but it got worse over a few weeks and the trans wouldn't upshift during acceleration. I'd have to back off the throttle for it to upshift. Dealer replaced the cat and it was fine after.

 

Ruled out an IAC or MAF going bad, or CAT :P

Good luck.

 

I had my mechanic go through yesterday and check everything, My EGR is completely junk, but i know the EGR has been bad for a while. There is no gunk either. He couldn't do a back pressure test as his meter was broken. I'm hoping it comes back that it is broken so i can get this back to where it was.

 

Had em cut the CAT off and bam did this car come back to life. Thanks for all the tips guys.

 

ConGrats