recently i noticed whenever i am at cruising speed or any higher speed and i take the car out of gear or just disengage the clutch the car drops to 1500rpm and pulses back and for worth between 1500-2000 rpm at a even pace.. i have checked all vacuum lines and cant quite seem to locate the problem. anyone else experience anything similar? once the car is stopped at a light it idles normal, the pulsing only seems to happen while the car is cruising at a higher mph. its nothing serious just abnormal and a little annoying... ive tried searching but honestly cant figure out the correct search terms to get the answer i am looking for lol

 

Hmmm mine will pulse but opposite when i pull to a stop it will throb from 1200-1900 like 3 times then stop. I just thought it was its catching its breathe i like to see what others say too...