Mazda 626 Forum : “when started n Idle/running, rpm bounces between 2000 to 3000 & keeps on bouncin...”

when started n Idle/running, rpm bounces between 2000 to 3000 & keeps on bouncing...

I dont know, I started from my office to home, when i started my car, rpm was 3000, then it came down to 1500, then its keeps bouncing between 2k to 3k. Then I thought might be cold problem. So I let the engine run for some time. But no effect it is some problem. I don't know Wat is it. I kept my car at office and drove back with my friend. Please suggest me any solution...