Today i noticed that my maxima gets stuck in high RPM in idle.
I Stop and it stays at 1400 for a while than drops to 600... when i tap the gas it again goes to 1400 and stays there for a while... sometimes dropping to 1000 then going back. (The car is fully warmed up after freeway driving)

What could be the cause?
I dont feel any strong knocking as from a failing injector.
Could this be the knock sensor? i dont have the check engine light on.

Thanks

 

If no engine check light is on look for a reason that would not trip a engine check light. Sounds simple but its not. Sometimes there are stored codes on your ecu that might give a clue to the problem.

 

i had this issue on an accord after the timing belt got changed.

turned out to be a vacuum leak

 

sense we have MAF driven cars any vaccum leaks after the sensor itself will cause this issue so check all the lines going to and from your resonator box or aftermarket intake if you have one. If you dont find a line off or loose or anything post up again. It just sounds to me like unmetered air is entering the system causing the idle or throttle to hang up. Think of it as idle if the ECU wants a higher idle it will let more air in through the idle air controll valve. Likewise if theres a leak somwhere letting unmetered air enter the intake tube the ecu must compensate by taking that extra second or so to let less air in through the programed way (iacv) to compensate for the "bad" air coming in. so FIND YOUR LEAK