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What he said, the 1jz coilpacks get hairline cracks in the plastic, therefore making the spark ground out to the head, losing spark. If thats the case take a dremal and v out the crack and fill it with apoxy "temporary fix". Ive also heard the 1jz coil packs arent the greatest under more than stock boost, they tend to get spark blowout, you can compensate this with a DLI or running your gap a little tighter. this solved the problem for me, mine was falling on its face at wot around 12-13 psi tho.