Seat Ibiza Lambda Sensor Problems

hi, im still having problems trying to find out why its missfiring when at low revs but it clears at 2000 revs but when u change gear it continues all through the gears, its really doin my head in now i cant afford to keep pumping money int...

My car gave no warning to my problem it just strated jerking while trying to accelerate in low gears now it dose it in all gears and is getting worse by trying to cut out while in motion, i have had the coil packs change the lambda sensor a...