Nissan Almera loss of power

My partners Almera every so often, sort of goes into limp mode, lack of power, loses revs, when setting off from traffic lights, roundabouts or when in slow moving traffic. Engine management light comes on, it comes up with throttle sensor. Had it into Nissan & they changed throttle body, 10 days later it lost power on motorway in a average 50 speed check zone. tapped a few things under bonnet & got it going again then about 50 miles later it did it again doing about 65mph on m/way, tapped under bonnet again & got it going again. Could be ok now for another 3 months or so. Any ideas.