So my cousins just finished swapping a gsr into his ef. The motor starts but when he presses the throttle, the car bogs and backfires. So he wants to sell the gsr long block for 600. The compression on it is ok and I was wondering if it would be safe to buy the long block or is there something wrong with the motor and I shouldn't buy the motor. Any advice would be appreciated. Thanks for looking

 

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