93 prelude problem

I just bought a 93 Prelude Si (H23A - Manual). The interior and exterior were both in good condition, car has 78,000 miles and was only $1500. It has had the engine swapped, another H23, with 60,000 miles. I was aware it had engine trouble but it can be fixed...hopefully. The car starts up and runs, but doesn't idle well at all at any rpm. Also, the car won't rev over approx. 3000-3500rpm(tach not working). It gets to a certain point and starts sputtering at that speed. Occasionally it will rev higher, but right after the engine bogs down and idles real low. While cold, the car runs, still not passing the 'rev limit', but is driveable. After about 5 mins of driving, the car slowly starts losing power, and won't even rev to that 'limit' anymore, then it completely dies. After restarting it, it barely runs...if it can even be considered running. Idles very, VERY, low, and if given any gas usually dies. Also, there is a strong scent of gas while it is running, at anytime. Flooding? The guy I bought it from had the ECU and distributor cap replaced. I've checked the error codes, and the only one it is showing is 23 (knock sensor). Could the knock sensor be the only thing causing all of this? Any other ideas of what it could be? I would appreciate any suggestions.

I'm still trying to learn about my car but I made a stupid mistake by changing the spark plug wires around. I don't know if it might help but I gave it a try

Update. I crawled under the car to remove the knock sensor to see if it was damaged and discovered it wasn't even screwed in all the way. I finger tightened it as much as I could, reset the ecu, and started the car. No more code 23. The car runs a little smoother, but it is definitely running too rich. There is a VERY strong scent of gas whenever the car is running, whether your sitting in it or behind it, and the gas mileage is not even funny. Is there anything I can do to reduce the fuel flow?

I would check vaccum lines. One time I was changing motor mounts on my old tempo and a vaccum line came disconnected and the whole thing reeked of gas and ran really rich and sputtered at a low rpm. check grounding too. Although, you probably already checked those things.