Idles low and jerks at low KM's

Car in stationary position idles quite low, not very smooth idling.
Car jerks between 30 - 60 KM's (only at low KM's) not high KM's. On a slight decline and in the correct gear, car jerks between those KM's, once I accelerate more, the jerking goes away. It does not seem to jerk at all when driving on an incline at low speeds when more acceleration is needed (if that make sense). Only jerks on a straight or slight decline.
It does not jerk in high speeds at all.
The MAP sensor (no MAF) has been replaced.
The car has had a service.
The cables and spark plugs have been replaced.
The idle control valve was cleaned thoroughly, and the jerking went away for a time, but has since returned after I went on a long journey, car went extremely well in high speeds. But since then, the car seems to have developed the jerking again, and I cleaned the idle control valve thing again, but has not helped.