Mitsubishi Repair: Car stalls when idle or slowing down, mass air sensor, mitsubishi galant

Question
I have a 92 mitsubishi galant gsr.
recently, the car have been stalling when i come to a stop.
this doesnt happen during short drives or when the engine is cold. (eg-3km to the supermarket)
after a longer drive, and the engine is warm the car will stall when i come to a stop.
this doesnt only happen when the car is idle.
It also happens when i have the clutch in for engine breaking.
this doesnt happen all the time. sometimes when the car is idle and hasnt stalled, the car is revving lower than it usually does.

when the car is in motion, there is nothing wrong. seems to go fine.
this problem only occurs when the car is slowing down to stop.
again, the car drives perfectly fine when cold/driving short distances

Answer
Joon,
The ignition system should be inspected; spark plugs, ignition coil, plug wires.  A faulty charging system can also cause this type of problem.  The battery and alternator should be tested.  Other areas to check are the intake system (mass air sensor, air filter, idle air controller), fuel system (fuel pump, fuel filter, fuel injectors), and even the exhaust system (EGR valve, O2 sensor, catalytic converter).
Good luck!