Fuel pressure car is still hesitant?

Which engine? 2wd or AWD? What do you mean by hesitant? What does it actually do? Any CEL or other lights on? Flashing? What did the pump pressures do during testing?

OK, that sounds like reduced power mode, what codes does it have? There are a lot of items that can trigger reduced power mode, fuel, ignition, transmission all can trigger it, even an issue in the braking system can cause it. From the "kicking back" it sounds like ignition or timing. So please list any codes it has in all the systems.

OK the first two codes are both circuit codes, IE a wiring issue. The first one is an open circuit while the other is a short to ground, both on the same circuit. Those are the wires from the valve on the rear of the engine to the ECU. The other code has to do with the first O2 sensor. I would check that area of the harness over, it could be that the wiring got close to the exhaust and melted to it or was otherwise damaged. Especially as those codes could all be a result of harness damage.

Hello, for that code (P0090) I am getting "Fuel Pressure Regulator 1 Control Circuit/Open", so a circuit code is different than a performance code. The wiring diagrams show the fuel pressure regulator being 2 wires that go back to the ECM. So although you replaced the high pressure pump, this is going to be a issue with either the wiring/connector pin issue with the control valve, or an ECM fault. Ill post the wiring diagrams for you. This is just a two wire valve, looks like a White wire and a Pink wire at the High pressure pump. The Fuel Rail Pressure sensor will have 3 wires. If you have not changed the oil yet after the new pump installation, I would do that as well before driving anymore. When the high pressure fuel system has an issue and things go out of balance, a GDI system will always end up with fuel in the oil, which causes an overly rich condition as well. See if the oil is over filled or smells like gas,
Let me get the wiring diagrams for you so you can check the wiring to the ECM, I know the ECMs on these vehicles is usually right in the engine compartment next to the air filter housing.

Heres the service info for this code, diagrams 2-3 show the GDS (which is the Hyundai factory scan tool), but the live engine data is the important part, you can still check these same data PIDs on an aftermarket scantool. Diagram 5 is the aftermarket wiring diagram and the rest are the Hyundai oem PCM wiring diagrams. Diagram 9 is the PCM pinout so you can check the wiring from the Fuel pressure control valve to the PCM. Notice on the oem wiring diagram that the control valve has it's 2 wires twisted, so the White and Pink wire at the High pressure pump harness you may find twisted together. This is the best way to ID the correct wires for the control valve.
It looks like there are no connectors in between the control valve and PCM, so that makes things a little easier.
Let us know what you find, or if you need further help.