I have an 07 base auto and since I bought it, it occasionally revs on its own from 750 to about 1100-1300 rpm. I cleaned out the EGR valve, throttle body, the EGR passageways, and the intake manifold, replaced the spark plugs, water pump, both belts, tensioner, motor oil and valve cover gaskets. Nothing has been able to take the idle surge away so far. I’ve also been averaging about 13 mpg city driving very lightly, and when I disconnected the battery to clean the parts, when I reconnected my battery my mpg was restored to about 18 city for a week until it dipped back down to 13. When I do dip back to 13 mpg I noticed a sound that isn’t there when my car was doing 18 mpg.

 

here’s the link to how the engine is sounding. If anyone can hear something that may sound odd please let me know.

 

Are you getting any engine fault codes? Also, is the idle jump only during when the engine is cold, warm, or both?

 

No fault codes and the idle surge happens at all temps. I notice the surge when I’m either parked at idle or at a red light.

 

I was just going to ask the same thing.

@CitiUA7, what you're doing is throwing parts at the problem; this is virtually always the most expensive solution. I strongly recommend you get the codes read and have the issue professionally diagnosed. The thing is, it could be one or two lazy O2 sensors, the IAC valve, or simply low coolant, or all of the above..., or something else entirely. Until you have it professionally diagnosed, all you can do is guess, and yes, you might actually get lucky, but at this point, you've already cost yourself more than what it would have cost you to have the issue professionally diagnosed and fixed.

 

I believe the IACV is only present on 2G and earlier 'drive by cable' throttle bodies?
OP try the idle relearn procedure on the provided attachment. If that does not work, like horseshoez states, a professional with the proper scan tools may need to evaluate the car. In addition, it may need a throttle position learning check.

 

I’ll try to see if that fixes my idle, thank you.

 

there is a ribbed section of pipe from the air filter box to the throttle body. Those tend to develop cracks and cause air leaks into the system


EDIT: when you did the valve cover gaskets, did you also do the spark plug tube seals? Check for oil on the spark plugs.