P38 occasional hard brake pedal.

2001 4.0L . Occasionally the brake pedal goes hard when needed. The brakes will stop the vehicle after a good hard push. When the system is de-pressurised it takes 30 seconds for the pump to get to pressure and turn off. It then takes two presses of the brake pedal for the pump to cut in again. The accumulator has been replaced ( with a new one ). But the issue is still there? Could it be that there is an issue with the pressure switch in the abs pump? And if so, is there any way to test it? Any advice on how to progress warmly welcomed.

Something not right there, with a new accumulator the pump should kick in every 4 presses

I guess there could be air in there somewhere. Or maybe the brake switch itself is acting up so you're not getting the power assist.