Nissan Repair: 2004 Nissan Xterra engine problem, 2004 nissan xterra, mass airflow sensor

Question
Hello! I own a 2004 Xterra with about 45,000 miles. A few days ago it developed a problem that is difficult for me to describe, but I'll try. It is idling very rough and a little slow, with a quite noticeable vibration. The tachometer needle bounces about 100 RPM  at idle, and while accelerating it seems to hesitate once or twice a second. There is an occasional "knocking" noise while driving, and the car sounds as if it is about to die when coming to a stop. There are no warning lights or check engine lights illuminated. The problem came on fairly suddenly and seems to be getting worse. Is there anything obvious that I can check or direct a mechanic to?

Answer
Ben,

First, an analysis of the engine is in order.  That is, a mechanic will check the timing, fuel pressure and leak down of injectors to see if the timing is correct and the fuel pressure is proper and not leaking down.  Leaking down would mean that one or more injectors are stuck open.  Other things to look for is a defective mass airflow sensor.  They can go bad without throwing a check engine light.  I would run a tank of premium fuel with a Lucas fuel additive.  Nissan does not recommend fuel additives and they are smart as many melt injectors.  Lucas does not and actually provides octaine and lubrication.  A small bottle will do if you have crud in the fuel lines it should clear things up.  If not, the first things written are those to be looked into.  Email me back if you require more.