We had a similar unexplained problem like that. We ended up having to have the computer re-flashed.I have a USA 2005 Suzuki Reno, 2.0L, 16v Dtech, automatic, 155k, oil changes every 4k with air filter spark plugs oil filter. Cam Shaft Sensor was bad for acouple of years. Recently replaced cleared codes no codes showing. Vehicles started stalling or hesitating when in stop. And now will hardley start without fully depressing gas pedal.
Have scanned no codes it was all erased after cam shaft position sensor.