u 5MT user ?? The gear shift is like that sometimes stuck, need push harder. I've been driving for a month plus now. Not only 3rd gear, but all of them will get stucked out of the blue.

U getting engine stalled is due to your manual skill not good enough lor :-P
There is 0.5second lag the moment you hit your throttle and the moment u see the rpm rise. So u must hit the gas first before you release clutch. That's y the car stalled coz u used to the no delay throttle response from old car with throttle cable. All newer cars these days use drive by wire.

Idling around 600rpm is normal for this car. The tchak sound is from the aircon compressor thermostat.

Go back Proton change their gear oil ??