Had a car dropped off to me to have the turbo setup finished up, wiring finished, and any little thing the last "builder" didn't finish. Then get it started and sent over for tuning.

The car is a 95 prelude with what's suppose to be a built sleeved H22 by Laskey racing, head is unknown as of now, has springs, titanium retainers and s2 pro 1 cams with adjustable cam gears set at 0. Assuming new valves but dont know yet for sure.
Has an all in fab intake manifold with fuel rail(I welded in the removable injector bungs on the fuel rail as I didn't trust them and had 3 almost pop out completely) and ktuned 80mm tb.
Sheepy turbo manifold and intercooler, with what looks like a 60mm turbo.
Gas tank was just cleaned and coated inside and out, walbro 450 intank pump, 8an feed, 6an return, aem fpr set to 43-44 base pressure.

Harness is a rywire race harness, ecu is an aem v2, 3.5 bar map sensor, gm iat, aem wide band o2, aem epm, and cop.

Long story short I fixed everything I could physically see that was wrong and got the car running. It starts fairly easily, but no matter what I do it keeps popping and backfiring.

Things I have tried, not in the exact order but done them all, sometimes multiple times to be sure:

-Checked and adjusted the valve lash to spec
-had my tuner over to help setup the timing in the ecu and get the timing and fuel where it should be.
-double, triple and quadruple checked the physical timing.-Compression checked out to around 180 across the board(assuming 9:1 compression as it was built years ago. First start since it was built probably 5-6 years ago, potentially more)
-Leak down test checks out good on all cylinders.
-Had the injectors tested and they were clogged up from sitting so replaced them with a brand new set od id1050's as the old ones would not come back in spec when cleaned and tested multiple times.
-New plugs x3
-Cleaned the SS fuel filter (looked fairly clean)
-Cylinder 3 always looks sooty on the top of the piston so to make sure that injector isn't spraying more fuel I Swapped 3 over to 4 and no difference in 3 being sooty and black.
-Also tried swapping injector plugs 3 to 4 and changed it in the ecu, still no change in 3 being black and sooty, so the wiring to that cylinder seems to check out, returned it back.
-Checked the cam gears to make sure they had a key in the keyway. Also compared oem gears to make sure the marks and the key way lined up incase for some reason they were a bad set.
-Put stock cams and gears in to make sure the pro1's not being degreed wasn't the issue. Ran the same.
-even did a smoke test on the intake manifold and see nothing coming from the gasket or the injector bungs on the manifold side of things (my next step before pulling the engine out and apart is to pull the intake manifold off and welding these bungs solid, good idea, terrible application, especially on the fuel rail, very dangerous)
-took the aem epm apart as I had issue in the past with the bolt coming loose on them and checked it all over and it all was tight and looked good.
-tested every coil with my spark plug tester and they are all firing.
-all sensors look to be working as they should.
-tried fuel up and down, no matter where I put it I can't get the backfires to stop.
also tried the timing from 0-2500, at 0 down to -14 columns, at 16 degrees originally, tried it at 30 degrees and tried it at 0 degrees, no difference.

Only thing I can think of is the bungs on the intake manifold have a slight leak that doesn't show on the smoke test but are sucking enough air on all the cylinders except 3 causing it to be super rich.
That or something internally that doesn't show on a compression or leak down test.

Has anyone ever ran into something like this before?
Been doing this stuff for a long time and never had something stump me like this.
Figured this is the best spot for a problem like this cause if anyone would have ran into this issue, I figured it'd be a tuner.
Any help is appreciated.