Precision350z

Hey guys, have an AEM Infinity 8 in my car, was tuned properly by a reputable shop. Always ran perfect, no troubles. I've just put in a new built motor, with 280 degree cams, and a new intake/Throttle body. Started the car for the first time, ran great for about 20 seconds, luppy as hell ofcourse but stable. Then the car started to increase RPM to anywhere between 2400-2900 and hold.. At 900ish to 1200 rpm the car had about 15inHG vacuum. Been checking for vacuum leaks forever, can't find one, and really not thinking thats the problem. Any ideas?

Thanks, would really appreciate some help!
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