I have a Kartcher G2500PH. When I use the high pressure fan nozzle the engine will idle down like it's over pressurizing. I have looked at the nozzle and the hose and it works fine with the low pressure nozzle. When I pull the trigger it sprays hard then the engine will kick down and then up, so I basically get a pulsating effect of high pressure for about 2 seconds then it kicks down for a second and then back up. Is there any adjustments I can make? I can see the throttle moving with the change in pressure.

Thanks for any help