2004 Aveo Engine Codes...again

So first of all I would like to list what I have already replaced on my Chevy Aveo since August 2011:
Air Box
Air Box Hose
Serpentine Belt
MAP sensor
Catalytic Converter
Thermostat Housing
Battery
Timing Belt
Water Pump
Alternator
Plugs and Wires
All Fuses
and Brakes, Pads, Tires, Air Filters, Oil Filters etc.

Here is what is STILL wrong with the car: Throwing Engine Code P0420, rapid deceleration whenever gas is not depressed, occasional acceleration (uphill) when gas is not depressed, intermittant loss of power at high speeds, tail/brake/dsl light intermittant failure, DSL display light intermittantly turns off, occasional failure to catch when trying to start the car (all systems go, but it can't quite get there), heavy fuel smell when starting... oh, and I need a new wheel bearing.

So here's the thing. I feel like these must all be related. I can't possibly need another new cat. Is there some sort of Aveo "syndrome"? Any electrical fix that anyone knows about? Am I the only one this is happening to? Please advise.

Sounds like you've got a fuel pump and/or throttle issue for most of those. I'd start with the fuel pump. What is DSL btw?

Sorry, that was supposed to be DRL (Daytime Running Lights). :)

What is the current mileage? You listed a bunch of repairs, but what were the problems you were having that caused you to make some of those repairs? (I assume the belts / WP were regular maintenance) Don't know if you did this work yourself - if not, do you know how dirty the inside of the throttle body was/is?
Do you have a complete oil change history for this vehicle? I don't think the 2004 Aveo won any awards, but regular, correct, lifetime maintenance helps improve the odds.

No offense, it doesn't sound like a throttle or fuel pump issue. Sounds like you need to replace your o2 sensor, unless you have an exhaust leak.

P0420 Error Code: Catalyst System Efficiency Below Threshold (Bank 1)