are my fuel injectors bad on my 1994 j30t j30 infiniti?

[my 1994 j30t infiniti]

my car has 189,000 miles on it i replaced the spark plugs,pcv valve,and fuel filter...and the mechanic checked my car out and said one of my injectors is bad is this why my car idles so low it feels like it wants to die out at time? also one mechanic said there is a misfire somewhere? when my car is running and its in park it idles normally now when i put it in drive the idle drops and the car shakes but then if i turn the ac on the idle goes back up what do u think the problem can be?

 

[Robert M]

Sounds to me that you may have a dirty idle control valve. Somewhere near your throttle body, there is a computer operated valve that controls the amount of air that is entering your engine at idle. It is normal for these valves to collect engine oil vapors over time, and require cleaning. In your engine compartment there is a tune-up decal that ordinarily will show you where this valve is located. While you're there, go to a do-it-yourself car wash and shampoo the entire engine bay. Also, find your PCV valve and clean it, as well (it also collect hot oil vapors). When you put your AC on, the computer automatically raises the idle speed (via the IAC valve) to accommodate the extra strain caused by the operation of the AC pump. If you think you have a clogged injector (not very likely) go to the auto parts store and buy some Chevron fuel system cleaner, using it according to directions. At this mileage, you should consider a thorough de-sludging treatment. If you want to know how, E-mail me!!! Good Luck!!!