Typical tune-up time. Don't be that guy who replaces every expensive part on his EFI system only to find out he needed new plugs and wires. Just because platinum/iridium plugs are supposed to last 100k miles doesn't mean that they do, and don't loosen, or crack the insulators, plugs wires go bad no matter how much of a"high performance" product you purchase. I prefer the lifetime warranty types so it's free after the first set. It's not hard to do in these vehicles.
The flying saucer thingy is not an FPR. An FPR would have vacuum power (typically), and a fuel tank return hose. It's also nearly always on the opposite side of the fuel rail from the supply line. It's a fuel pulse damper. In these cars the fuel pressure is managed by varying the voltage to the fuel pump, so there is no return line to the tank. The other part you replaced is the fuel sensor- that's what measures pressure, temp, etc to give the PCM it's information for the fuel pump controller.
As far as TPS testing goes, I seriously don't test those. TPS problems are exactly like what you're experiencing, fairly distinct, and rarely does it fail so that a test will actually show you something. IINM, you can test for voltage reference while operating the throttle and you'll see 1-5v between 2 of the pins as you move the throttle.
You do not need a special tool, but you do need an understanding of how the TPS fits the throttle plate shaft. You'll figure that out if you pay close attention to what's going on while you remove the old TPS. You will need a torx 15 screwdriver (at least I did) then remove both the screws holding the TPS while not pulling the TPS out. Let go of the TPS, and watch it. It should tilt towards the air intake away from the engine (might go the other way, not sure since I don't have a Zetec). Anyway, you see how it tilts, that's how you put it back on. The worst mistake you can make is to force the TPS on by lining up the screw holes first- line the TPS up on the shaft, then rotate it to make the screw holes line up. If it doesn't fit flush without any force, then you're doing it wrong.