first thing to do would be to check if the CEL is on - if it is, there are stored codes that need to be read. those can often help point you to what might be wrong
If you do not have an OBDII code reader, most chain auto parts stores will read the codes for free - if you can get the car to them. They wont clear them, but will tell you what they are. If there are codes, make note of what they are, in the order they appear - will usually be in a "PXXXX" format with the Xs being numbers.