hey guys,

Well, I don't know if this is very normal, but sometimes when I rev the engine to about 4k and let the revs fall back down to idle speed. Sometimes they dip under idle speed down to like 600rpm or so and the come back to a smooth idle.

this doesn't happen all of the time but it happens, I have K&N FIPK, Berk 50mm Header and Megan Racing Drift Spec exhaust.

 

Normal, one time it even stalled (1 time only)

It's the ECU adjusting

 

i have that issue a good bit when i have the a/c on

 

it's even more pronouned/hesitate with AC.. if it's really bad then maybe vacumm leak. All cars auto/standard/make model will dip below standard idle then spring back when you blip the gas in neutral (just some are more evident then others).

 

maybe the MAP WHACK! trick could help.

 

that was my initial reaction was when i read the title... a vacuum leak. If it is minimal, may just be ecu adjusting or a very small vacuum leak on your intake. Replace the lines...its cheap and can free up hp, save you gas if it is the problem.