Rb25 misfire on light throttle

[redline racer510]

I have a s1 rb25 and until recently everything was running fine. Yesterday morning i decided to run an errand and after warming up for a couple minutes i pull out the drive way and give it gas and it starts to hesitate and misfire until i give it half throttle or more. If i accelerate rapidly it hesitates for a second until it gets passed acouple thousand rpm and then it just accelerates like normal. I noticed when i it hesitates my widband reads full lean and it feels like its hitting a fuel cut or something and the sound resembles a wrx or something. I checked my sparkplugs and they are properly gapped and look normal as far as coloration but any insight would be very helpful?

[redline racer510]

I also noticed that if I hold the throttle at a set rpm vacuum starts to increase and it starts to lean out until it reaches full lean.