...when we test drove it today there was an issue with the transmission, when the dude did diagnostics it said that the oil temperature in the transmission was -19, which is obviously bullshit, causing it to operate in emergency mode hence the car not really doing much when throttle applied. I called another electric and he said it is most probably a PCM issue...
The tranny temperature sensor is in the TRS (Tranny Range Sensor - inside the transmission, but has external connector for PCM harness). With a little luck, maybe there's a wiring problem between it and the PCM - broken wire, or maybe a poor/corroded connection at the TRS or PCM. I'd say that's more likely than bad sensor in the TRS or bad PCM.
Check that the connectors are fully mated. People have been messing with the wiring, so maybe one connector was not put back completely. There's a connector C107 in the middle of that wiring harness that includes those temperature sensor wires. There are two similar-looking in-line rectangular connectors beside the brake booster. Those connectors are known for causing problems - often caused by corrosion - might just needed to be separated and re-mated. I do believe that C107 is one of those 2 connectors.
You might also disconnect the vehicle ground at the negative jump post for 15 minutes to reset all the computers, and then reconnect. It's a long shot, but sometimes strange problems are fixed by a "system reboot".
You could troubleshoot the wires and connectors using Section 8W in the FSM (any year '02 to '04 would work for this for your car), but the wires between the PCM and TRS for this are violet/pink and dark blue/black - pins 3 and 4 on TRS, and C4 pins 34 and 35 on PCM (schematics and connector pinout diagrams are in FSM section 8W).