My altima with a 2.4l has a bouncing idle at a stop and sometimes it even stalls. No CELs but i hooked up a scan tool to it and got a p0325 code for a knock sensor malfunction. Do knock sensors cause a bouncing idle and stall? I couldn't find any oil leaking from the valve cover gasket or on the distributor. And the MAF sensor is clean. could it be the knock sensor? I know where the knock sensor is but why do some say it is difficult to replace? any advice would be great. thanks!