Problem I have

I don't know what is causing this problem but here it goes. Sometimes after I have parked my car and come back to it after a few minutes or even hours the car starts to rev up after starting it up, I don't know what can be causing this.

Another problem I have is when my car is cold, usually first thing in the morning and I try to drive it it has a jerking motion when I put it on drive, I'm afraid this might be causing some damage, the problem is that when I drive it to the garage it doesn't do it because the car is warm.

Any suggestions would be helpful.

tHanks guys

RaZor