Ok so I had a guy plug in his scanner and he found a code on for my front right o2 sensor. Thus with this code its maxing out my injectors and dumping fuel, thus making the car run really really rich. It does smell rich and will slightly stumble on cold starts when taking off. I probably get like 6-8mpg in town. Would this be true?

Just a run down, my car has a mail order tune and is Speed Density. I have my rear o2 sensors deleted. Stock fuel injectors. Rest of my mods are in my sig.