1990 Holden Gemini losing power uphill

My car is losing power up hills to the point that I have to stop and turn the engine off for 5 to 10 min and start engine again and then its ok, but it will happen again if im driving up another hill. While driving uphill the car seems to jerk as if its not getting enough fuel.
The car never does this on flat roads, only on long climbing hills. But not consistantly, sometimes it doesnt do it at all.
Ive changed plugs-leads-fuel filter and had a service but to no avail ! WOULD LOVE SOME ADVICE AS IT HAS BEEN VERY DANGEROUS IN SOME OF THE LOCATIONS IVE HAD TO STOP, THE HIGHWAYS WERE I DRIVE DONT HAVE MUCH ROOM IN THE STOPPING LANES. THANKS