2007 Kia Rio base has fluctuating RPMs and slight lurches and hesitation.
What is your question?
No codes; no failed parts detected
new spark plugs, gapped to 45 and not fouled
1 new coil pack; 3 older but in good condition
Alternator is fine
MPG has not decreased
Vehicle experience misfire like lurches at idle, while accelerating, while slowing down, really at any time although it does not have a set rhythm.
While experiencing misfire like lurches, RPMs will either drop or surge, spanning anywhere from 500 RPMs to 1500 RPMs at idle. However, the RPM fluctuation does not occur in sync with the lurches at all times. Occasionally the RPMs will fluctuate and no "misfire" is felt, and vice versa.
Could this be a Mass Air Flow sensor going out or possible fuel system error?
What makes this problem better or worse?
idling out of park feels the most lurching; like at a red light
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Hello, fuel, air, ignition spark testing is really needed. It's likely something is happening here that is causing the intermittent drop out. Way too hard to know without performing hands on testing and eliminating possible causes due to verifying proper operation of the different components and systems. I don't think too much about jumping to the "mass air flow sensor" fault. Unless ignition spark is dropping out, it almost must be a fuel / air ratio issue.
