rough idle; clogged fuel injector; iat sensor

Try cleaning your throttle body and using a can of SeaFoam cleaner. You can buy both at Auto Zone for a combined cost of less then $12.00. It takes about ten minutes to clean the throttle body and you just pour the SeaFoam in the gas tank. I can't help you with the IAT sensor.

How do you know it's a clogged injector? Are you getting any Check Engine lights? A failed injector will generally give you a "Injector Circuitry" or "Injector Leak" ECU code.

First thing I'd do is run some injector cleaner through the system (Techron cleaner is good). Then clean the throttle body. Both are easy and cheap. I'd remove the throttle body to clean it rather than trying to clean it on the car. You'll need to buy a new gasket for it, but that's really cheap (< $10).

Second, replacing the injector should be a last resort. If you do replace just one, it must match the others. There are two "styles" of injectors, one has a blue dot, and one has a red dot. They are essentially the same, but they MUST all match. Otherwise, the ECU won't be able to adjust the fuel flow rate properly. And it's alot of labor, so consider replacing all

I replaced all 6 of mine, so I'd be happy to give you some help if/when you do yours.

Get a service manual. Chilton and Haynes are decent, but an OEM shop manual is better. It will pay for itself the first time you do a repair yourself.

Bill G '91 SE Auto

'91 Maximas did not have variable valve timing.

Bill G '91 SE Auto

i figured out what the flutter noise was, i have a small exhaust leak. thanks for all your help

Nissan injectors are pintleless design. Running any kind of cleaners are not recommended and will not do a thing.

Good read