big vacum leak makes my car runs better? w t f....

[tractorsosa]

k, here is the deal, i did replace my standalone for a c2 ecu in order to reduce the power of the car, and slowly make it look more stock,

first of all when i plug the new ecu with the c2 software, the car starts just right up, let it run for a lil bit, and i found a big vacum leak, then sealed with my hand and the car stalls and shuts off,
now the car is hard to start and doesnt idle good, unless i give it some gas, otherwise it will shut off again! what i am missing here?

leak was found in the big plastic hose from the mnfold to the block off plate in the valve cover,

i have the correct injectors for the tune as tuner recomends,

[tractorsosa]

nobody?