91 Max SE intermittent rough idle

Folks,

I have 1991 Maxima SE 5-speed with 160,000 miles on it. I've owned the car from day one and it has been rock solid everyday. However, I'm having a strange problem with the idle. Intermittently the idle will rise and fall between about 500 RPMs to 1300 RPMs. Eventually it will settle down to about 750 RPMs and runs smooth. When it gets down to the 500 RPM range, you can feel it that its about to cough and sputter but the engine will start to rev back up so no stalling occurs. Running the A/C naturally tends to cause the problem to occur more frequently.

I'm not sure how to go about diagnosing the problem. I've checked plugs, wire, cap, and rotor. All are good but I did discover one wire wasn't securely fasten to the cap which gave me hope that I had found the problem. The problem occurred again while at a drive-through during lunch. Afterwards I checked the wires again and they were all secure.

Air filter is new and the gas filter was last change around 100,000 miles. However, my gut tells me it something electrical. I say this because I think I started to notice the problem shortly after changing the alternator. The original alternator died and I replaced it with one from an auto electric shop which apparently had something wrong with it too since it caused me to be left on the side of the road a day after replacing it. Because I had to have the car early the next day, I couldn't wait for the auto electric shop to fix the rebuilt alternator and had to settle for an el-cheap-o from Auto Zone. Could this possibly cause the problem or could the failing original alternator have caused an electrical component to fail?

One last thing and I know I'm reaching but thought I would provide as much information as possible. Since the price of gas has gone up so much, I've been using the 85 octane gasoline as oppose to the 87 octane and 93 octane gasoline that I normally have used through out the life of this car.

Thanks for time and help. rick.

Reply to
RHopkins
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Cleaning the throttle body cures a lot of rough idle problems.

See

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Click on "How to", then look under engine.

Al Moodie.

Reply to
Al Moodie

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