I have an 03 G35 Sedan with 176K on it and recently when I start it u and I'm idling it idles really low for about 4 seconds as if its about to shut off and then goes back to normal. I took it to my shop and they didn't find an issue and suggested trying a tune up. Anybody else experienced this issue?

 

Sounds like a vacuum leak! Check all your hoses, those that connects to both valve covers, intake ports etc.. make sure they are properly clamped tight and no holes on them.

It happened to me when I installed mrev2, driver side vc hose was wiggled when I put everything back.

 

Thank You. I will try this