300U hydraulic very hot ??

OK got the metering drilled out to 0.031", no screeching etc, all works BUT it is really hot on the steel lines and the tank under the seat. I mean way to hot to touch with fingers. Is this normal?
It would sizzle spit on the tank.
It also seems to be a big jump in RPM when lifting with cylinder, big horsepower just to run the pump.
It had been run for about an hour in 70 degree weather. Fluid is the cheap stuff from Tractor supply, yellow bucket, 333 compliant.
Just wondering if I missed anything.
tx in advance

No, this is not right. Your system is staying on high pressure all the time. That is why it is getting hot and also why engine rpm increases when using cyl as what ever you are operating with the cyl takes less pressure than the pressure system is staying on when it is supposed to be in neutral. First make doubly sure none of your single to double setting are moved too far. Bent or broken pin. If they are ok, something is wrong in regulator valve. Gasket covering hole, orfice not open or something misassembled. A gauge right in the side of the regulator block will quickly show you what you have. One at coupler will not show bypass pressure which should be well under 100psi.

OK just to be clear, when using cylinder to lift, is like taking a big load off engine-rpm goes up, but it sounds better, more relaxed: less load.
So-single to double settings? means what? ???
exactly...?
all pins seem ok, assuming you mean external;all good, greased
"side of regulator block" means on the narrow side ,I assume, where there is a plug?
And "coupler" ? I have 1 cylinder and 1 valve box, and 1 regulator box. Hoses go direct from valve to cylinder.
tx again

The plug on the regulator valve is on the narrow unmachined side. It's purpose is to test the system. IH had a method back in the day and a gauge with hose hookup before the advent of flow raters etc. By putting a gauge, (2000 psi or more) into that port you can read the pressure when in neutral and when using the cylinder. The only time you should read full relief valve pressure (1200 to 1500 psi) is when your cylinder reaches it maximum stroke, or if you dead head the valve. To do that, being you say you only have one valve you would need to disconnect cyl and plug outlets. No need to do that as long as you can extend your cyl to the end of stroke and hold lever to read pressure. When valve is in neutral, you should read less than 100psi.
Far as single and double, that was the main design advantage of this style system. You turn the valve setting to single and you then develop pressure only one way with lever so therefore you can lower a single action cylinder without loading hydraulic system. Some times the pin gets bent or worse, if it breaks you can bend in internal linkage that turns the spool inside. In that case you would have a difficult time getting single and double action without removing and repairing the internals. At any rate, that system has to have a low pressure free flow in neutral or you will ruin pump and all O-rings through out system.

Avoid running the tractor, except to troubleshoot, at this point. Speaking from experience here. If you keep running it like it is, something is going to give. On mine, it was the o-rings between the pump and lines.

Sticking out the front of the hydraulic valves are shafts with two flat sides. That is your single-double acting selector. Turn it 90 degrees one way, single acting. Turn it 90 degrees the other way, double acting. Put it somewhere in the middle or past either "sweet spot", and you have problems.

There's supposed to be a pin or some other notch that lets you know it's in the right place, but it could have been ram-rodded at some point in the past.