engine has loud gurgling but no CEL
 

There is something wrong with my 99 auto maxima. It has about 45k miles. Yesterday i started noticing that the idle was a bit different (jerking). Today after i came home and opened the hood there is this gurgling noise coming from around the manifold (really loud). Nothing is changed on the car performance-wise anymore (only have a muffler). There is no CEL light and i don't know how to run codes or if i even need to run them. Will some1 diagnose the problem.

thanks