Clutch does not engage

This happen when the engine is completely cool down. However once the clutch has engaged and the car can moves on smoothly. However, I notice that the petrol consumption has became on the high side for my normal driving.

I tried to start the car from cold this morning. I engaged D gear without pressing accelerator, the car just jerking and not moving forward for ten minutes. After that I press on the accelerator, it start to move slowly with slight jerking feel. Then move it for 30 seconds and shift to parking gear. After few seconds, I shift back to D gear, only then it moves by itself slowly as usual. I have not changed the clutch. Due to gear oil leakage, I replace the oil seal and auto gear oil.

It is an automatic transmission. Due to transmission oil leakage too, I changed auto filter, auto gasket, oil sump gasket and fill in johnsen power steering fluid.