when I hit any kind of hill over 50 mph my engine/power/revs starts hesitating/sputtering.
This is a new occurrence? My 2.5L does this all the time without throwing codes. Did you completely replace the TPS with an OEM unit? The TPS can't just be cleaned out like the IAC valve and sensor can.
I would do as mukluk
said and make sure battery connections are clean and tight, then proceed to the fuel system. It sounds like the issue takes place only under the most stressful load, so problems may be hard to diagnose when the Jeep is sitting still. You may be able to connect a fuel pressure gauge to the rail and use a long enough hose so that the face of the gauge can be taped to the windshield or run into the cab, then cruise a hill on the highway to see if pressure drops or jumps around when you notice the sputtering. You may need to bleed the pressure before attaching the gauge though, maybe someone else can chime in for safety's sake.
The in-tank fuel filter is supposed to be a lifetime filter but I suppose it could get restricted somehow. FP regulator is a more common point of failure though (which sits right on top of the tank so you'd still have to drop it). I know you can test the check valve by trying to blow both ways through it, which you shouldn't be able to do if it's working properly, but your symptoms don't sound like they're related to a bad check valve. You may be able to check this before dropping the tank by having a buddy turn the ignition on so you can hear the fuel pump fire up for a second, repeat on-off several times in succession to draw fuel into the lines then keep your head near the tank and listen for fuel to trickle back into the tank through a possibly faulty check valve. Not sure why that would cause problems under load though - usually bad check valve is associated with problems starting the Jeep. Hopefully someone else will chime in, good luck!