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I looked through the instructions for the Edelbrock E Street system and it requires 50-60psi on the fuel feed, so that means you had to have installed their fuel supply system if it was running. The other thing I noticed is that the E-Street ECU does not control the engine spark (no spark map, no EFI distributor) but instead simply says "Set timing to OEM requirements". It's only a fuel controller, and seems to me that the only thing that could cause it to be running that rich is the wide band O2 sensor getting blinded by an exhaust leak, allowing ambient O2 to be sucked into the stream which would tell the ECU to dump in fuel. The E instructions are crystal clear about the importance of the exhaust system being leak free around the sensor.

If you're confident with the O2 sensor I'd concentrate on the ignition system, and verify that it's all good. I would think that you want your base timing to be around 12 degrees, and around 34 to 36 all in for the street. Two things come to mind - 1) are you changing out the plugs after they're fouled, or just cleaning them up and putting them back in?; and 2) have you verified that you don't have one of the counterfeit MSD units that flooded the market a while back - Counterfeit MSD 6AL Ignitions | Consumer Alert