its like that because youve probably gotten the wrong MEC chip type
when you get the wrong MEC chip type the car runs like ass basically
whilst there are s1 and s2 ecu's, there is different MEC chip types for some wierd reason and if you get the wrong one, it runs like ass
i had a mail order remap long long long time ago s2 GTST with S2 remapped ecu, it ran like ass, turns out i got the wrong MEC chip type
so essentially, you can't use it
remaps are junk, you should never buy a remap
if you insist on remap, remap your current known working ecu with nistune