I have a 1997 Hitachi 330 that is experiencing engine speed issues while working. It seems to start after about 45 minutes of use and is intermittent, occurring every few minutes or so. What happens is while working at higher RPM (normal working speed) the engine will drop down to an idle mid-use which starves the hydraulics of power. The problem resolves immediately upon letting go of the hydraulics. I have checked the fuel filters, including the screen in the banjo bolt near the pump, and there does not appear to be an issue in fuel supply. The engine also doesn't try to starve and stall, it just rests at an idle. I am leaning towards there potentially being an electrical or mechanical issue with the switch in the cab. Let me know if you have any ideas, thanks!
Welcome to HEF Rocky ! There is a pressure switch mounted on the swing motor on the side. That is the dig pressure sensor and that controls your auto idle. Make sure that switch is good. Will your machine rev back up if you travel?