Keep in mind, I've been putting in Petrol-Canada 87 in my car for majority of this. Also, the idle has always been steady and consistent. The spark plugs were also done back in August.

So I've had a JDM GSR swap in my civic for almost 2 years now and it hasn't given me any issues up until maybe a month ago. It started with an engine code for my O2 sensor because something was causing my car to backfire and trip it. I fixed the rotor and cap in the distributor but that didn't fix anything so then I did the O2 sensor. The car was still backfiring but the CEL wasn't coming up for the O2 sensor anymore. The next thing I did was replace the fuel filter and then added STP fuel system cleaner to the tank on the following fill up. That initially fixed it but a week later it was backfiring again so the following fill up I used Lucas Oil injector cleaner/cylinder head treatment which helped a bit (This fill-up I used Shell 91). It backfires every now and again so I'm not too worried on this issue anymore.

Now here is where my current problem arises from:

A couple days later, I replaced the stock fuel pump with a walboro 255 but after 2 days, I put the stock one back in because it was pushing too much fuel for the injectors to handle. When the car accelerated from a standstill, you'd feel it hesitate and lose power then after the pedal was pressed down enough, it would eventually pick up normally again. Ever since I put the stock pump back in, the car hasn't felt the same. Not only is there a lack of power but even while accelerating, it feels like it's losing power while going up the rpm range. 2 days ago I decided that I should only be running 91 like I'm supposed to so I filled up with 91 from Petrol-Canada. When I was driving yesterday, it continues to have a lack of power like before but now while going up the RPM range, the car hesitates bad to the point where it will hold the RPM at whatever it's currently at but won't accelerate more than that. After pushing the pedal far enough down, the car comes back to life and jerks forward a little bit then continues to do it again every now and then. This doesn't happen every time I drive though as I have done some drives late yesterday and today where it didn't do it at all but the feeling of losing power while accelerating was still there. While I was on my way home today in the evening, I kept an eye on the RPM as I was accelerating on the highway. In 5th, when the needle hit around 4000 RPM, the feeling of losing power came in and it stayed where it was and very SLOWLY would continue to climb. (Pedal was held in the same position) Once it passed a certain RPM, it was normal again. This is also not WOT, the pedal was pushed down just enough to get the RPM to climb. I checked the MAP sensor to see if it was getting the right voltage too and it was (3.something while off and 0.70s while idling (DC Current set to 20 on a multi-meter)), the next thing I'm going to check is the TPS sensor and see if it's also getting the right amount of the voltage.

While waiting at a red light today in the morning, the idle dropped from 900 down to 600-700 then back up to 1500 and settled back at 900 again. It did it again right after at the same light and hasn't done it since. This is the first time the idle ever acted up like so, so I personally don't feel like it's an ignition issue because the car starts up fine every single time for the most part and even near the top of the RPM band after the secondary butterflies open it's running good. After I check the TPS sensor, I'm going to clean the throttle body plate and do a compression test along with inspecting the spark plugs. Later this week I'm going to install a fuel pressure gauge to see if it's getting the right amount of fuel pressure then take the car to my friends shop so he can inspect the injectors. If it still keeps acting up after that, then I might go ahead and replace the coil and then the igniter if the coil doesn't help.

I honestly don't know why it's doing it. There hasn't been a code since before I replaced the O2 sensor and I can't even use a scanner because I'm running a virgin JDM OBD1 P72 ECU. I plan on running RDX injectors in July with the walboro so that's when I plan on actually tuning it. Does anybody have any ideas as to what could be the issue? I'm stumped.

 

Update:
I tested the TPS sensor and got 0.45v on closed throttle and 4.53v on WOT and there were no dead spots while opening and closing it. I also tested the K-ohms on the spark plug wires and according to the helms, they're all well below the 20 k-ohm limit. I'm starting to think it's either the pump or the injectors.

I picked up a coil and ICM off a CR-V and already tested the coil. It read 0.9 ohms for the primary and 15.7 k-ohms for the secondary. I don't really think it's the distributor but I'm gonna check it anyway. Very rarely the car will take longer then normal to crank over. I'd have to stop cranking because it takes too long but the second attempt starts it no problem. More commonly, sometimes the car starts but it feels like it momentarily tripping and stumbling it's way to a steady idle rather the normal start up I get most of the time.

Still going to do a compression test as well and check the spark plugs.