Mine was actually from the EGR diaphram itself. Deleted the whole system the first time the engine came out and haven't had a problem since (with a boost leak on the back of the engine anyway).
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90 300zx TT 12.731@114.00 94 Camaro Z28 13.751@101.83 03 WRX 13.973@94.88 02 Mazda MPV; four kids and a wife don't fit in the Z. 90 240sx (sold) 16.9@87