Original Post:
This is a last resort... i've run out of ideas here.

Got the motor setup and put it ~9months ago... sat for a while cause i had my permit, i've put around 3000miles on it so far.
Setup is a sr20de motor, t25, MR tubular manifold, 370s, tuned ecu + safc, 3" dp test pipe and exhaust.
Im looking to solve the problem, not hate on the sr20de/t. (which sucks at this point.)

Problem: it has slowly died since i started driving it consistantly. After it got done, and when i drove it occasionelly when it was sitting.. it pulled real hard, at 7psi just like a regular det would, spun first no problem, drove easy, no bucking and bullsh*t, good mpg.
Now, it idles crappy until warm, definately doesnt have the power it used to have. Has something wierd between ~2000-3000rpm when it feels like the clutch is slipping, or something is holding it back, like a lean spot, but its not running lean there. gas mpg is absolutely horrible. It pops, backfires, and bucks during shifts and sometimes at partial throttle.
I've run a wideband on it, and partial throttle in 3rd, 4th and 5th gears is too rich, around a 11.8, but wot is ~12.0

It just doesnt pull like it used to, i've checked ignition, fuel, wideband, turbo etc etc etc

Looking for any idea that might help, thanks.

 

regular oil changes in those 9 months right?

give plugs a try

edit: did you check o2 sensor voltage and fuel pressure?

 

yea, def... new oil as soon as it was in, new oil at ~500 and just new oil after ~2700miles

plugs are straight, so is fuel pressure. Ill check on o2 voltage, what should it be at??

EDIT:
I think i figured it out...
with the help of my friends expertise, we're pretty sure its the knock sensor.

A lot of people suggested it was a timing issue, and a bad knock sensor will pull timing, and wont set off and ecu code.
The other reason is becuase, after some research, most ecu/rom tune companies will pull out the knock sensor signal at wot, because it cant handle the noise. I dunno if this is just something nissan knock sensors do, or maybe other companies as well.

Im gonna get the base time set right at 17* and pull the knock plug, see if that helps. It better damnit.

 

t was the timing... somehow, it was wayyy to far retarded. so, we reset the timing... and the car runs **** again
I might possibly need another MAF when the tps was pulled (the ecu runs of the maf then) it had a crazy miss, and made it mad hard to time.

After all this... i get home, and post on sr20forum.. Apparently its the second mark from the RIGHT, not the second mark from the left. I guess i should get on fixing that.... so im still running at 15* retarded god DAMNIT

but even still its back pulling pretty hard like it should. I dont think the knock sensor had anything to do with it. Its fu*kin fun to drive it again though
ordered a new coolant temop sensor, new vac lines, and i'd like to get my ecu done right with JWT or possibly a Calumsult program.