Please help, '84 318i 'surge' problem

Hi all...I hope someone can help. I love my BMW and need to know what I can do for it.

When I start the car (I live in SoCal) most of the time it revs up to 3000rmps and stays there. Every once in a while it will drop back down to 1500rmps but thats not very often anymore. We have tried to adjust the idle, no luck. It is a 5 speed, and when I am in 2nd, I dont have to press the gas cause of this.

Any clue as to where I might begin to search out this problem?

Thanks!