Car hesitates after 3500rpm

[TheDonEffect]

Hi,recently my car got an sr20det installed in it. Here's the scoop, I really need some help diagnosing this problem. My car will not pass 3500 rpm because it gets some kind of fuel cut, like the feeling you get when you run out of gas. I initially thought it was the fuel pump (was using the stock 240sx pump) but I just upgraded it to the wallbro 255 one. The only difference is that now the cut isn't like a hesistation, but rather a wall, instead of abrupt hesistations, it just sorta hits a wall at 3200 rpm or so. At rest, the car revs all the way to redline, i could even hold the rev at 5000 without even a sputter. I could pull in 1st gear all the way to redline without a problem. But in any other gear, this problem occurs.Ok, now this may sound dumb, but I'm using a sock as an airfilter, so I thought maybe it was the sock since without it the car wouldn't hold idle, kind of like the same problem but only higher. So I added another sock to increase the restriction (which is weird since we all upgrade our filters to more flow more air) but still the same problem. I originally had a problem where the car wouldn't even hold idle and just die on me, but the sock fixed that. I have an airfilter coming in today or tomorrow so I'm good with that. But would the airfilter really fix it, because I mean c'mon.I'm thinking it is probably the sock, since the MAFS are sensitive beyond belief as I found out, but I don't know exactly why since the sock does provide ample restriction.So in summary, car revs fine at rest, and pulls in first perfectly, but in any other gear, the car just hits this wall liek a fuel cut, right around where the turbo should really be kicking in. It used to be a abrupt jerks, but now it just hits a wall (not as abrupt as before). Fuel pump has been upgraded to a wallbro 255, and running essentially a sock for the airfilter. I'm thinking it's the sock, but then I thought it was the fuel pump as well, read my nissan manual and it said it could be both. Just wanted to see if anyone else out there had the same problem. Sorry about the long post, I will really appreciate any feedback. Newbie to the sr here, lol.

[PS13t]

Have you replaced the spark plugs and checked the gap?

[Scott McLellan]

I know somebody with a turbo beetle that has the exact same problem. He took it to the dealer to have the turbo system replaced and after they did, his car wouldn't rev above 3K. I had no idea what it could be, but it's weird that the dealer gave the car back to him with this problem.

[C-Kwik]

Check the spark plug gap. Turbo cars need a stronger spark or smaller gap as they have a denser mixture. At rest, the turbo is not boosting or at least not as much, so the problem would not make itself evident.

[TheDonEffect]

Hmm, spark plugs, didn't hear that one yet, reading through the forums seems that everyone mentions the MAFS. When the plugs were put in, they were gapped correctly. But here's the funny thing, the car no longer hits a cut at 3000 rpm, it just stumbles a little aroudn 4000 now and hits a cut somewhere up there now (didn't have the insides to go further). The car drives fine under normal situations, just really rich. Gas mileage is still decent though, so it isn't exceedingly rich, but still very noticeable rich.