Hello I have a Caterpillar 3208 with 300 hours on my tug. When I first got the boat, six months ago, everything was fine but, towards the end of a trip from Mexico to San Francisco Bay, I started noticing an uneven rpm when idling bellow 900 rpm. To start the engine when cold, now I have to give it some throttle so it won't die. Once it has run for a few minutes then, a consistent up-and-down variation in rpm occurs when bellow 900 rpms. The problem goes away at about 1000 rpm or gets somewhat reduced when I put the engine in gear. Seems to me that the engine has some problem regulating the low flow of diesel. In an attempt to fix the problem I removed the fuel injection pump and governor assembly. I cleaned the governor and replaced it's springs. After putting it back the exact same problem was still there. Has anybody experienced this before? Any suggestions on what to check next? Maybe I should replace some other component in the governor like the thrust collar as someone suggested? Any help would be greatly appreciated. Jose Sousa MV Jade Lord Nelson Victory Tug 41