i have a 02 nissan sentra ser and i got a enigine light on my idle goes up and down sometimes and if anyone could tell me what the problem is i could replace it i thought it was the throttle postion sensor but advance suto don have that on there comp for that car so maybe im wrong [/align]

 

What is the check engine light code (you can get it checked for free at autozone), for the idle going up and down, check your pcv valve first (see if its stuck), and also check your IAC (idle air control)valve for kinked lines and check to see if its bad. you might need a chiltons or FSM to find the resistance values on the iac and perform an ohms test.