Engine RPM fluctuates about 300 rpm???

[Hungry Man]

I may have just got some old gas from a small town station.  I have an intermittent fluctuating rpm issue.  It will run at 3000rpm and then drop down to 2700 for a second then back up.  I added 1/2 a tank of new gas from a high volume station and the issue is much less present but still there.  I was told fuel stabilizer may fix that issue. 

Does anyone else have any thought's?  I am worried it is an engine issue.  It only has 160hours on it now.  Otherwise it runs perfect.

Thanks,

Hungryman.

[lesman01]

most likely it is gas. usually the first time out each season, I have to run it about 15 minutes with the symptoms you describe and at WOT to pump through any bad gas. That usually takes care of it. check or replace the fuel separator and look for water in the filter. Check the plugs as well.

[Capt Rick]

The engine ECU moniters the Air and water temperature. In order to bring the engine to operating temperature it tell the throttle to go up 300 rpm then the ecu see the rpm change and drops it back. The temperature of the water in the summer is high enough were it stops the faster. The colder water temperatures takes longer to reach operating temperatures.

So in summary it is normal to hunt +/- 300 rpm when first runnning engine.

Capt Rick