I recently installed a Perrin Turbo inlet hose on my 02 WRX (VF30 Stage 2.5 w/ larger tmic) and a greddy type -s bov and now have a whirlwind of problems!

First of all, my Turbo inlet didn't come with the necessary nipples and fittings so I had to purchase my own. I did T it off as the perrin hose does not come with all the necessary holes. Anyhow, I started up my car and it ran great. It idled at -20 psi and everything ran smoothly. I then installed the Greddy Type-S bov and plugged the recirc hose. The car ran like total crap. I kept hearing a shuttering noise and jerking and the car ran pig rich. I said screw than and stuck the stocker back on. Now when I start it, it idles at -15 - 16psi vac instead of the normal -20psi vac. I checked for vac leaks and couldn't find any.

Now for the weird part. I took it for a test drive and after a WOT run in 2nd gear the car began to shutter at high boost. It started making the noise/jerking around 6k rpms all the way to redline. Afterwards I put it in 4th gear and I overboosted up to 19 psi!! I normally got 17.5 psi with the cobb stage 2.5 with a spike of 18 max. The shuttering is still apparent in all gears... I then threw a p0302 and p0304 (cylinder 2 & 4 misfire). I reset the ecu and the CEL's were gone but I've been staying out of WOT. Also, when I start up the car it doesn't sound smooth, it makes a very slight dying sound then starts up.

Could it be fouled plugs? I just replaced the plugs a few months ago with NGK platinums heat range 7s. I honestly can not find any vac. leaks anywhere and this predicament is driving me insane. If it's the plugs or vac lines then why would I be overboosting... Argh.....

Can someone help a brother out?