Need Help With CRX

[CRX-Sweetness]

First question, is there anyway that I can run the numbers on the engine in my ’90 CRX Si to see if the engine I have is the one that was original when it was made?

Second question, has the EFI system ever been know to need replacing? This is what’s goin on. When I bought it the car it didn’t pass DEQ and the Check engine light had come on which, I was aware of. I figured it to be an O2 sensor that was out. I took it to an Import shop and they did some diagnostics and confirmed that the O2 sensor was bad. I changed it and took it to DEQ again and my NOx tripled and my THC’s went up as well, but the CO and CO2 maintained well below acceptable levels. When it is cold, it runs just as shitty or shittier than it did before but when it is warm it seems to run ok. I still have a fair amount of power but the exhaust smells bad and when I put some gas into it, smoke is visible. So does that suggest an EFI System problem? It is pretty clear that this engine, if it is the original, was at least taken out, due do plenty of evidence (which is the reason for my first Q). Could it be a vacuum hose hooked up wrong, which if there was one in the wrong place, I could only assume it wouldn’t run right.

Final question, if this engine problem proves to be something not worth fixing, how would I be able to obtain a low mileage JDM engine of the same kind that is in my CRX (the D16A if I’m not mistaken)? or, if I will in fact pull the engine, is there an engine with a little more power that can bolt right into the car with no or almost no alterations? if there is i might as well. but I’m going to college so I don’t have time to put into a high performance engine that requires a lot of altering to fit or I would. I need something reliable that runs good. Any help on these would be greatly appreciated. Thanx.