03 S60 T5 rough idle/power loss
 

Hello, I am 42 years old and have a 2003 S60 T5 with 55,000 miles that I have owned since new and was used primarily by my wife until recently. It has been a great car but last year our family needs required more space so I purchased an XC90 for her. I then took the T5 and cleaned the cheerios out of it and retired it for only nice driving days. I am not a big time gearhead but I had read many times that the T5 had some hidden potential that could be unlocked by a flash of the computer and some intake and exhaust upgrades so about six months ago I purchased a cold air kit and exhaust system from Eurosport Tuning along with a computer programmer from Rica. Once modified the car really came to life. Much more power and efficiency. As I said I don't beat on it but I run it through the gears once in awhile. Well about a month ago I turned onto a street and accelerated with normal power when all of a sudden the car hesitated a bit then lost power. It felt like two of the cylinders went dead. I drove it straight home and it has been sitting in the garage ever since. Now when started the car idles rough and smells very rich. I am afraid my performance upgrades have hurt my car but I hope not. Anyway can anyone tell me what may be wrong? Do you suggest I just take it to the dealer and listen to their bantering about how I shouldn't have messed with the car's computer and such? Any direction is highly appreciated. Many thanks! Chris.

Return it back to stock and see how it does.