I was driving my car home from the gym, and for the first time since i've had the car its been [unintentionally] out in the rain. Due to this I had the air conditioning on. After like 2 minutes of driving the SES light came on (which it does occasionaly). While the air was on, the car seemed to have a slight sputter going on. The RPM's were remaining constant but it did feel like there was alittle bit of sputtering every now and then.

Back when we got the car last year it kept throwing code 45 and had some very hard sputtering (almost bucking at highway speeds) and we took it to a chevy dealer and they diagnosed it as a bad fuel pump. The fuel pump and fuel filter were replaced at the dealer. The car still throws code 45 every now and then, but hasn't had any problems as far as drivability or anything. I am wondering if something is starting to go wrong again or maybe it was just lugging alittle bit because the air was on (i never use the air, so i dont really know how the car acts with it on). Any suggestions on what to check or possibly replace?