First of i would like to say Hello MB memebers.

I just recently bought a 1987 300e, and let me tell you that its a very fun car.
but holly sh** i just cant figure out why my idle jumps to 1.5 - 2 RPM then drops to 750 after 10 min. when i got seafoam it started running better, rpms where about 900. but after 2 days the same thing happenes it just stays on 2.
I just changed spark plugs and an air filter, still the same. i just ordered new injectors, hoping this is the cause to my problem.

Any one would know whats the problem?