125k km (77k miles), 1.2L four-cylinder engine, 84 horsepower, manual transmission, sedan, also known as Daewoo Kalos.

Important: There was a broken TPS wire (pigtail) coming from the engine harness to the throttle position sensor, which now has been spliced and soldered by a mechanic.  https://postimg.cc/HVrCn4WV

The problem is, after driving for a few minutes, then coming to a stop and idling, the rpm starts to rise, sometimes up to 2000 rpm. It's never stable and changes with the supercharger (e.g. when I turn the AC on it drops and then comes back up). The car behaves fairly normally when driving but the rpm needle jumps up when coming out of gear into neutral and then sometimes stays at 1000 or even 2000 rpm (regular idle is around 600-700 rpm). The car howls and wheezes worryingly when accelerating. 

The guy (mechanic that spliced the TPS wire in) tells me it's something with the throttle body itself and that I should look for a replacement used(!) throttle body. There is also a taped perforation in the rubber tube going from the air filter to the throttle body. https://postimg.cc/gallery/gWbPgvM

It doesn't trip any OBD codes. My OBDII device sometimes tells me (at random) it's not passing emissions from O2 sensor, ERC sensor and catalyst, however this is not consistent between tests.

Important, again: the rough idle issue is not present when the TPS is unplugged. Obviously, then the car doesn't drive well, but it's still driveable. If I unplug the sensor and start up the engine it trips P0122 “Throttle Position Sensor/Switch A Circuit Low Input.” Then, if I plug it back in and erase the code, the rough idle problem vanishes for a while. It usually only reappears after a few driving cycles.

Could it really be a problem with the throttle body? Or maybe something with the fuel/air mixture on idle? Or maybe yet, the TPS wire being soldered wrong?