2004 Mach 1 engine light on?

I have a 2004 Mach 1 auto. It has 410 gears, K&N intake, borla cat-back, and a dyno tune. I bought the car with 16,8xx miles and just hit 17,300 the other day. Everything was fine when I parked the car then the next morning I went to start it and the engine light popped on.. I took it up to the local auto zone and the guy said its because of the cold weather and the intake that's on the car. This makes no sense to me because I thought engines were supposed to run better with folder air. Right? The car smells like its burning rich, I have bad fluids changed but the lights still on. Any ideas on what's going on or what I should look to replace first? The cars parked for winter so I have plenty of time to work on it. Any replies would be greatly appreciated.