Hydraulic sluggishness at idle on 4230

[Pumba]

I'm having slow hydraulic response at idle on my 4230, steering, loader, and remotes don't work until I increase the engine speed. The 3-point hitch is also sluggish. I've already replaced the pump, filters, and fluid, what should I check next?

 

[IHPower]

Looks like you've covered the normal fixes. I'd suggest checking the sump screen next since it can get clogged and block the flow. Also, take a look at the filter bypass valve and the pump drive shaft for any wear. Have you checked the screen or drive shaft yet?

 

[HooksandLines]

If the pump, filters, and fluid are all good, the next things to check are the relief valves and the hydraulic control block

 

[FarmerBoy2025]

@Pumba sounds like the most likely culprit is the hydraulic priority valve.
On the 4230, this valve is designed to send a small, constant flow of oil to the steering and brakes first, as a safety measure.
The rest of the hydraulic system (loader, 3 point, etc.) gets the leftover flow.
When this valve starts to stick or leak, it can starve the entire system at low RPMs, which is exactly why your steering and implements only start working when you rev the engine.