Rough/Bumpy Idling

Over the past several months, I have noticed what I perceive as a rougher, shakier idle. I only feel this when stopped, and it seems rougher when the car is warm - ie, not noticeable when starting it up in the morning. Also, not sure if it is related or not, but occasionally, when accelerating onto the highway, I feel a jolt of power with no extra pressure needed from the gas pedal.



Wondering if this is something to be concerned about or not. Not looking to make unnecessary repairs, but I would like to be taking good care of my car. Fuel/filter issue? Spark plugs? Something else completely?



Hoping for some straight forward advice here. Thanks in advance!



2005 Mazda 3 - 62k miles - manual transmission

Before you can get any straightforward advice folks would want to know anything you can tell them about things like spark plugs, filters, etc. All original? Does your maintenance schedule include any service that you haven’t had done? Minor problems like this are often as simple as basic maintenance items. Is the check engine light on?

I have been following the regular maintenance schedule per the manual. Service through 45 k at the dealer (ouch!) and since then at my local mechanic with the exception of oil changes which I have done at the quick lube place every 4k or so. I am fairly certain that spark plugs, filters, etc. are all original. The check engine light is not on. I brought my car in to my local mechanic for the above complaint and he tried what he referred to as a “fuel line cleaner,” but I have not noticed any change in symptoms. Thanks for your help!

The first thing that I would do is actually go ahead and do all the basic tune up items - this basically means new spark plugs (wires are also best to do), fuel filter and air filter. Also have someone check the fuel pressure and check it for vacuum leaks.

Even if the tune up items don’t “fix” this problem, it still just goes down as good car care and isn’t all that expensive. That’s partly why I’d do it first without spending any time or money on any kind of diagnostics. If you do these things and it still shows these symptoms, then you start hunting.