Rb20 won't start

[proxy0000]

Hey guys, I've searched all over for an answer to my problems but SRs are apparently more popular than the RB20...

Here is the situation :

My fuel pump crapped out on me so I bought a Walbro 255 and installed it. The car worked perfectly fine and then the engine just died. It was fuel cutting every time I tried to rev it past 2k rpm. A couple of attempted start ups later, my fuel tank meter stopped working.

I thought it may be the fuel filter, so I replaced it. Same thing happened - the start up was great, and I could rev it however high I wanted. A few minutes later, it started to fuel cut again, and it died. Now the engine won't start.

It cranks, but no start. I heard a cluttering sound every time and couldn't hear my fuel pump so I tested it. The pump itself works (wtf).

No apparent leaks or cracks in my vacuum hoses - can anyone diagnose the problem?

Could it be my spark plugs? And if not, then what could it be?? Argh.
And... if they are my fuel lines - how am I supposed to replace them?...

Any information would be nice.