Nissan Repair: the idle and engine, air control valve, leaky injector

Question
hi there. i have a bluebird ARX 1993, the problem is that the idle doesnt work properly it goes up to number 8 and down to zero very fast and even when working it still goes a little up and down standing between rev zero and one which less than normal. also there is a noisy sound in the engine when i first start it in the morning that makes the whole car is shaking until is hot but still the engine shakes but no noisy sound in it although i have recently changed the spark plugs, the air filter, and the engine oil and oil filter. help me plz as the car is still consuming too much petrol

Answer
James,

If the engine is using too much petrol I would be looking at the fuel pressure to make sure you do not have a leaky injector or two and that the fuel filter is replaced.  The up and down idle could be attributed to too much fuel and the engine compensating to attempt keeping it at idle.  Also, I would check and possibly replace the idle air control valve.