'02 Grand Prix, driving me insane

Alright, went to drive the car the other day. Didnt have enough power to climb a hill, then check engine light came on. Took it back home and hooked a computer to it. It set a code, which was the EGR. I wasnt sure if it was a EGR or a cloged converter. So I replaced the EGR valve, now when you revv the engine while in park it makes a very loud roaring sound. Also still has no power?? It also set another code PO300 which is a generic miss fire. It sounds like the loud roar is coming from beneath the car, right where the converter is. Ive narrowed it down to these possible things, a bad mass air flow censor or a bad converter.

So my question is, could it be a cloged converter??

The car has the 3100 series engine, with around 127,xxx miles.
It was my daily driver.

Couple things...if the EGR is stuck wide open this will hurt engine power.

Sounds that you might have a leak somewhere (??)

Welcome to AF.

It would help to post your mileage and the specific EGR code (DTC) since there are several.

Converter is possible since 2001-2002 models with the 3800 VIN "K" and VIN "1" engines may have been flaky from the factory. We have an advisory notice from GM posted at our Tips & Maintenance subforum.

Click here (http://www.automotiveforums.com/vbulletin/showthread.php?t=681283)