Most of these are pure junk. Literally a 5¢ resistor that makes a temperature sensor on your engine report false values to the engine computer in the hope of fooling it into dumping more gas in and advancing the timing. The only tuners that do some good are the handhelds or PC-based models that actually interface with the engine computer and modify settings with software that has been tested with your vehicle model. Of course these are a little more expensive than the fly-by-night ebay specials. I do not know if one is available for your car, which is essentially a Dodge Neon.
I would remove the 'chip', put in a couple cans of Chevron Techron injector cleaner to hopefully blast out the carbon in there from running rich for a couple of weeks, maybe change the spark plugs, and give it a good highway run. Hopefully that will return it to normal and you haven't done damage to your catalytic converter.