slight misfire at idle

[cmpltvertigo]

Hey folks my car, 2003 Vibe Base Model, recently started doing what I can best describe as a slight misfire (vibration). It is noticeable when that car is at idle such as at a stop light. I bought the car 2 years ago and have put about 12K miles on it (currently at 123K), so far the only maintenance I have done is replaced the air filter, intake gasket, and scheduled oil changes. Does anyone have any suggestions as to what it can be?

[Chiadog]

Fresh plugs wouldn't hurt, but if it is missing I think it would throw a code? Check the serpentine belt and tensioner. With a cold engine you can run the car for a minute with the serpentine belt removed to see if the "misfire" disappears. Next try cleaning the mass air flow sensor, I think it is just two little wires that are pretty well hidden. Search for threads here. Try to do things one at a time to nail down the actual problem.

[lannvouivre]

inline-4-cylinder engines naturally have balance issues that cause vibrations at certain engine speeds that increase with normal wear and tear. Newer Toyota engines, such as the 2AR-FE, have got a balance-wheel meshed to the crankshaft to keep the idle smooth as the car ages.

[cmpltvertigo]

First of all thanks for all the comments so far

Update: It looks like I may have been the victim of bad gas. The symptoms started with my last tank fill-up; I have since gone through that gas and filled up at my usual location and the symptoms have decreased by 90%.