Case 440 auxiliary hydraulic issue

[Skiddyscoop83]

I have a case 440 with hi flow that I'm having issues with the auxiliary hydraulics. When I have a rototiller or brush hog on and I use the tilt or lift it will slow the attachment down and it doesn't speed back up. I have to shut off the auxiliary switch and turn it back on. Sometimes I have to wait a few minutes before it will turn back on normally without the reduced speed and power. It acts the same in standard or hi flow with the exception that hi flow seems to spin it a bit faster. This I also do not understand as the motors on these are only rated to 20 gpm. So I would assume I would get all the speed I could out of the standard flow. After a long period of running it like this it will also get harder to get it to re engage. What I have done so far is checked and replaced the main pressure relief valve because it wasn't running at 3000 psi or at least I had thought this because I hooked a 6000 psi gauge up to the auxiliary quick connect and was getting very irregular readings. Sometimes it would be high and other times low . So I replaced it and checked again with the same issue but when I checked it at port on the control valve the reading was steady but high. So I adjusted it to 3000 . Still no luck the attachments still act the same but now when I move my lift arms and tilt at the same time I get a pretty bad hydraulic whine . One other thing to note is the self leveling doesn't work right . This machine has a self leveling valve that is only supposed to work going up and is always on there is no switch to activate. I have tried making adjustments to that valve as well with little or no changes.