MAP sensor problems

My 1992 swift 1.6 keeps surging during acceleration. The OBD says it is the map sensor but when i replace it with a known functioning sensor there is no improvement. Does anyone know how to fix this problem or how to get the OBD to function properly and give a more accurate reading? Is there any way to change the pressure in the exhaust system? Could it be a leak in the exhaust system? I have tried many things and cant seem to get it to stop. I know it can be fixed as suzuki calgary fixed this problem for me but it only lasted for 1 year. Then on the coldest day in winter it started again. It seems to be more severe when it is warm compared to cold. Any help would be greatly appreciated.