Nightprowler

So recently picked up a 1990 R32 GTR and must say Ive never had so much fun driving a car. Unfortunately that what has lead to my current problem. Car is fine when its cold but once it warms up it develops a stutter at under 4k or when accelerating at less than half throttle that gets worse the longer it runs but seems to got away at WOT. Car ran perfectly fine when I first picked it up drove it around in a spirited fashion but never really went hammer down. I ended up blowing off the the coupler that connect to the pipe that runs under the battery (I know Im an idiot) the first time shift out of the from WOT and then twice from 1-2nd at about 3/4 throttle. After the last time the car developed the Stutter.

Some from what I've been able to find the issue is usually caused by a Vac leak, the ignition timing being off, or AFM failing. Was wondering if you guys had any other suggestions or if anyone has had this issue before.