Low speed stumbling

My car is stumbling on acceleration, but only at low rpm's, below 2000 or so. It lurches a little, similar to if you engage the clutch to quickly. Once it's over 2000 or so rpm it runs smooth as butter. The exhaust also smells extremely rich. I have punched 1 cat as it was clogged but the other 3 are still in tact, I'm not sure how much of a noticeable difference that would make in the exhaust fume smell though. Any ideas what could be causing this?

KOER

32 (R) EVP - EGR not responding properly during test - EVP
(O,R,M) EVR - EVP signal is/was low - EVR
(R,M) PFE - PFE shows low pressure, EGR not seating or memory, not seating intermittently - PFE

44 AIR system inoperative - Air Injection

94 AIR system inoperative - Air Injection
Transmission TCC circuit/solenoid problem - Transmissions

KOEO

32 (R) EVP - EGR not responding properly during test - EVP
(O,R,M) EVR - EVP signal is/was low - EVR
(R,M) PFE - PFE shows low pressure, EGR not seating or memory, not seating intermittently - PFE

Cylinder Balance Test gave a 9, a-okay.

The miss only seems to happen when I'm at low rpms accelerating lightly. If I'm higher in the rpm, or on the gas a bit it drives fine. Fuel smell is constant.

Could the AIR codes be causing the problems? I am running 3 stock cats, 1 punched. Seems as though the entire smog system is malfunctioning. I'll try to check everything over, found some nice threads describing EGR and AIR operation;

http://www.stangnet.com/mustang-forums/821443-5-0-running-rich-pulled-codes-21-31-44-22-66-a.html

http://www.stangnet.com/mustang-forums/789737-1990-5-0-mustang-vacuum-emissons-issues.html

Do you think this could cause the problems? I'll have to fix it anyway as the car will have to pass a smog test next spring.

The fuel smell is noticeable on the highway so its making me think the bypass valve is constantly open since I wouldn't expect to smell tailpipe emissions from the cabin at speed. Does that make sense?

Nope, its just one of the cats thats punched. The honeycomb came loose and turned sideways completely restricting flow so I had to knock it out. So I suppose the smog system could be causing the problem? I should fix it regardless I guess since next year it'll have to pass emissions.