Need some help. I have a 2002...

[coltsneckbob]

Need some help.  I have a 2002 SR 340 Sundancer with 8.1 v-drives.  Sometimes at idle throttle settings the port engine is 100 to 150 RPMs faster than starboard.  This just started a month or 2 ago.  The starboard engine is always in the normal idle RPM range.   The port engine is inconsistent and sometimes (most of time) idles at correct (same as starboard) RPM. 

Now this week while in no wake zone and engines at idle speed (port was running correctly) with props engaged the port engine RPMs surged for a second or 2 up to 100 faster.  This happened 3 times  during this run while returning to the marina.  I replace the IAC (Idle Air Controller already,  but problem persists.  The hose from the IAC to the throttle head is clear.  

Anyone have any advice?

[wingless]

Has the intake been examined for leaks?

[coltsneckbob]

I looked over the engine yesterday. I did not notice anything. Though if a leak on the intakes wouldn't that be a persistent issue as opposed to the occasional one I am having?

[wingless]

There are several techniques to locating an intake leak.

Examine the options online to see if performing any of those actions is a service that falls into your comfort zone.

[PETERW]

Idle air control valve (IAC) is likely suspect. Check this first

[ATICA_II]

IAC replacement is about $75 found on amazon. Replaced mine and keep a spare on the boat