240sx 89' unstable accelerator

[bere240sx]

My car gives it to me a friend, it was parked for but of one year, I have carried out him several repairs, it finishes it that I made it was that of the injectors, it sent them to http://www.fuelinjectorclinic.com and they were as new.The problem that I have from the beginning you doesn't solve with that of the injectors, the problem is the following one: In the morning I power on the car and I wait to that warms to leave, when I accelerate the car to leave, the begins to give strong shakes, they ascend and they lower the revolutions, these raisin for several minutes until he/she doesn't make it but. However, when I am in a traffic light waiting to that it changes the light, the revolutions they ascend and they lower alone again, this passes between 800 and 1500. I have also noticed that when I stop the car suddenly, the revolutions lower so much that it seems that the motor will fade. which the cause of this problem will be?