Rough idle at cold start
 

1999 Civic LX with a D16Z6 1.6L vtec

When I first start it up, it will be around 1100-1400 rpm for a minute and drop to rough idle about 500 rpm if not less, I press the gas and get it about 2500 rpm (trying hard not to press real hard)

After a minute or so after that, if I turn off the engine and turn it over again it will be fine.

I'm thinking it's the idle air control or a vacuum leak. There is a sound that sounds like a vacuum leak near the cold air intake pipe.

Any advice would be appreciated. I'm new to Honda's.

Re: Rough idle at cold start
 

idle air control would throw a cel if fail. check your spark plugs and wires.
also the pcv valve at the valve cover somtimes when those are loose they can cause rough idle. and also if none of those fix the issue you can try using carb cleaner
take out the intake while the engine running spray some carb cleaner into the inlet air at the throttle body then rev the engine to clear it out see if that make any changes.
idle air can be sticky and may be a sign of fail in the future