I recently installed a vq35 in my maxima. The engine was rebuilded with new piston rings, ARP rod/head bolts, HKS HG and new Cosworth main and rod bearings. The only thing that was left alone was the rod and pistons. The car starts and runs but I'm having few issues.
1. Crankcase pressure. From where the breather hose, I'm getting vacuum and my whole crankcase is pressurized. If I unhook the hose, you can here the port whistle as it sucks air in, my pcv valve is working properly so what could be the cause of this? My idle is a bit rough and could this be the cause of problem #2?

2. I'm running on stock injectors and its running super lean. My WB is showing it idling at 21.0 A/F and only when I'm in lower gear @ 3-4k partial throttle does it goes down to 13.0's for a split sec and goes back up to 18-21 A/F. I"m getting a Flashing CEL when this occurs. I have 650cc injectors but I have yet to installed them because the stock ecu couldn't run with this, I just installed EU and I will throw these in there once I have a chance to see if anything would change.

3. I am burning oil like mad! I have a good amount of smoke coming out the exhaust and actually a little bit oil leaking out thru my y-pipe. The motor only has about 20miles on it, is this part of the break in process or do I have a broken/cracked piston ring?

I know this isn't in a 350z but since its the same motor essentially, I thought I post because I'm pretty desperate right now to get this thing fixed. Thanks in advance.