Fuel problem I think, please HELP!!!

[HamazingHwhisky]

I drive a 98 GS-T with a rebuilt 4G63t engine in it. I have a narrow band air to fuel gauge and when I'm driving the ratio will drop off the gauge, the car loses almost all power, and makes a loud sputter as it runs and as I give it any gas. I only have to engage the clutch for the fuel ratio to show up again in the stoich/lean and after riding the clutch for about 5 seconds I can put it back in gear and it drives fine again temporarily for anywhere from 30 seconds to 5 minutes... Then it happens again... and again... Anyone have any idea to what this could be?

I am also in the process of purchasing a logger and will maybe have a better idea of what's happening once I have logged this problem.

I just recently purchased this car and it's my first DSM. I have definitely already learned a lot, and will continue to learn I am sure. The car has a few bolt ons that I will list below.

~FMIC and hard piping
~3" Turbo-back exhaust
~Atmosphere vented BOV
(now wait, don't judge me, I bought this vehicle with an old Apexi BOV(also vented) that wouldn't hold any boost so I, being stupid at the time bought the newer version of the BOV so that it would handle the boost, and I'm not able to weld a new flange onto the hard piping... I didn't buy it for the sound, just the convenience at the time, and I didn't know it was necessary to recirculate...)
~Short Ram intake

Please correct me on anything if anything in here is incorrect as I am trying to learn

I am also pulling a few codes...

P1400 - manifold differential pressure sensor circuit
P0450 - evaporative emission system pressure sensor/switch
P1150 - fuel pressure solenoid malfunction
P0120 - throttle/pedal position sensor/switch A circuit
P0300 - random/multiple cylinder misfire detected

Thanks Again!

 

[viprez586]

Toss the narrowband, they're junk and innaccurate. Unless you like the annoying light show.

Recirculate your BOV and fix any other boost leaks. Perform a boost leak test.

 

[HamazingHwhisky]

Did a boost leak test...

my dipstick is letting air out so I changed my PCV valve and ordered a head cover gasket kit to replace those as those had minor leaks as well as between my BOV and flange...

How do you recommend recirculating my BOV?

I'm pretty sure I am unable to recirculate the one I have on there, and I am not capable of welding on a new flange for a different CBV that is recirculating, unless there is a way to get a recirculating CBV that will attach to this apexi flange? Or is there a way to recirculate the apexi spec II BOV?

 

[viprez586]

Get a different BOV, remove the pipe, have a shop weld on a new flange. Or run a GM MAF + translator so you can properly vent you BOV.

I'd do a search on those codes, I'm not that familiar with 2Gs.

 

[boostd_mitsu]

That evap code and the fuel pressure code are related, if your fuel pressure sensor in the tank is bad it will cause that emissions code