Fuel issue

[Turkj40]

2002/320 w 350 Mercs. when I was on a trip over the 4th everything was running fine at cruise, backed off throttle for a few minutes and my one of my engines would not go over 3000 rpm with no alarms. Changed the fuel filters ran great again for two cruises then it happened again when I came of trottle on my last trip. Runs fine just won't go over 3000 rpm in gear. Any thoughts or experience with this.
Thank you

 

[JimG]

Sounds like its going into "guardian mode"... the computer detects a problem and limits the RPM. If there are no beeps or other signs, you may have to get it hooked up to a computer to read the codes.