I'm finally giving in and asking for help...I generally try to fix things myself and by searching/fsm/etc. but I'm pretty much out of ideas on this one. This has been going on since I put the engine in last year. I've thought I fixed it multiple times, only for me to find out the next day or week or month later that it isn't. It's well past the frustrating stage lol. Sorry for the long post, but it's been a long year and I want to make sure you have a full picture of what has gone on

Engine:
1993 KA24DE in a 1991 chassis with S14 manual transmission
Ebay warm air intake
2.5" header, test pipe, greddy 3" SPL exhaust
1993 Auto ECU (have also tried 1991 manual ecu)

The issue:
Major lack of power, it flattens out at maybe 2000-3000rpm. (feels like it makes the same power all the way to redline as it does at 2000-3000rpm).
When running "normally" the car runs incredibly well, nearly as fast as my roommate's G35
There are no misfires, stumbles, etc. It just accelerates like i'm at quarter to half throttle.
I'm pretty sure it's not fuel related because I have an AEM wideband and afrs look fine

When:
The only pattern I can see is it seems that it mainly does it when it's hot (180 degrees), or when it is heatsoaked (from lapping days). Note: this is in general, honestly I haven't been able to determine when it happens or when it doesn't, it's random.
The only thing that ever seemed to fix the issue completely was removing the thermostat, so it ran at around 150 degrees at hottest, but generally was far below operating temp (ISIS 3" rad and clutch fan will do that) lol.
I've had it where it goes on for multiple days in a row as well as having the car run flawlessly for weeks. So far it seems that it spends more time running like a** than it does running good though.

Without going into issues that i've fixed while trying to hunt this down, here's what I've all tried (Issue was present before any of these things):
New Knock sensor
All emissions has been removed and blocked off including swirl control valves
Swapped TPS - used but verified working per FSM
New Fuel Filter
New Spark Plugs
New Plug Wires (well, used, but they were verified working and I tested resistance on them)
New Cap
New Rotor
Swapped Mass Airflow Sensors with a known good one and back again
Swapped coil pack/ignitor with a known good one
New PCV valve
All vacuum lines have been replaced with new ones except the brake booster one which i've tested
I've had valve cover, both upper and lower timing covers, oil pan off to remove timing chain guides, so there are new gaskets on all of that stuff
Have replaced the intake manifold gaskets
all new Fuel injector O rings
Swapped ECUs with a known good one
New Temperature sensor
New O2 sensor
Rechecked all grounds including sanding off any corrosion. I currently have a single 0 gauge ground from battery to a distro block and 3 4 gauge grounds out of that, one to side of strut tower, one to stock frame rail location and one to the intake manifold. I also have a 14gauge from head to firewall in stock location. checked all resistances and they are 0 with a multimeter

I've done diagnostic mode II for troublecodes and the only code I got was 33 for the o2 sensor circuit (just recently started having issues with the narrowband wire, so this issue is independent of that one)
I've verified timing is correct
I've calibrated TPS per FSM

I thought I fixed the issue earlier this year after I finally calibrated my wideband and realized the car was running lean under heavy throttle. Swapped fuel pumps and the car ran FANTASTIC for about a month.

The only issue (another issue i've been back and forth with but think I may have figured it out when I cleaned up the grounds) I was having was my number 3 injector would randomly shut off. It would usually go out after having the car off for a medium amount of time. It would run on 3 cylinders for about a minute then be fine. and sometimes during hard cornering the car would miss and go lean, can't verify whether or not it was due to this but I swapped injectors and replaced the clip with crimp on female terminals of the proper size (including soldering the wire to them to insure a good connection). This solved the issue for the most part, it did the 3 cylinder thing after that, but after I cleaned up the grounds and added a small one from the head to the firewall like stock it hasn't happened since.

The reason I feel that is pertinent to this is that the lack of power came back almost immediately. This doesn't make sense to me as my afrs are fine and the fact that the issue has been going on so long I don't think it's related.

Things I haven't replaced or swapped that I believe could be related:
Wiring harness - this is pretty much the only thing I can think of, but without figuring out what's going on, I can't fix it and I don't really want to swap harnesses unless it's a last resort.
Alternator - tested fine before I did the swap. I plan on testing voltages just in case but my guess is that it isn't an issue seeing as my lights and everything work fine.
Distributor/cam sensor
Fuel Pressure regulator - haven't replaced or checked since my afrs are fine

At this point I'm thinking it may be more related to the engine pulling timing than AFRs are good.

Any insight or ideas would be appreciated. I appreciate your time. I'm just want my car to run right! lol. I'm sure there are things I missed, but this is pretty much everything I can think of off the top of my head.

-Gary

I can think of a couple dumb things to check.

ebay warm air intake? Not sure what that means, but in my hillclimb days we ran into a pugeot turbo that would fall on it's a** under hard acceleration. It turns out the guy used some piece of radiator hose for an intake, the hose would collapse under vacuum and choke off the air to the turbo. Try a stock intake hose for the hell of it.

Another new distributor cap? If the vent gets clogged it can't let gasses escape and the air inside will start insulating the gap between the rotor and the wire pickups.

Are you sure the throttle cable is installed correctly? I would just make sure that with the accelerator all the way to the floor the butterfly is all the way open. Strange things can happen when you swap engines.

You could try getting an injector harness from a salvage yard, maybe there's still something going on with that. Good luck.

Ebay warm air intake = aluminum short ram air. It's not collapsing, also, the car didn't come with stock so i had to purchase this.

the issue started probably 2 weeks after I got the car on the road, guessing it's not that. (new cap)

Yes, throttle cable is installed properly

Yeah, I could try an injector harness.


Also, thought of something else. One big thing I've noticed is that sometimes it will lack power until 5300-5400, then it's like a light switch and it pulls much harder to redline.

I've had a lot of injector problems with mine. I have a 91 engine in a 92 coupe. I've searched a lot of threads here and people seem to agree that the injectors just don't last forever. I'm starting to suspect the ethanol in the gasoline is causing problems too. The little jelly gumballs can start plugging nozzles, sometimes they pass through, sometimes they don't. I'm out of ideas other than switching out injectors.

Check upper timing chain timing. Don't have any experience with SOHC, but recent experience with my DE was similar. Hard starts when hot, stutter and lack of power.....