I have a 1990 civic lx sedan 1.5 L dual point fuel injection. To start off the original engine was replaced by a lower mileage 1991 version engine after it was messed up by a previous owner not checking oil or coolant levels. Prior to that owner it belonged to my younger brother who had to replace the transmission after an incident involving a large unavoidable rock in the 2 lane highway with oncoming traffic.Post new engine install there has been multiple issues from map sensor, rough/high idle, fuel surges, hard time starting (even after replacing the wiring on the ignition switch), battery drain, and more recently gas in oil. Map sensor, O2 sensor, temp sensors and sending unit all replaced. I still have the original engine, fuel intake, and intake manifold available. I continue to have high/rough idle, fuel surges (which get worse the lower the gas tank gets), and the computer continues to throw code 5 which is the map sensor.Can any one help me figure out what might be causing these issues? Sorry, posted in wrong forum.
Edit: replaced battery after it started having to be jumped to start, so battery was bad. Planning to change out carburetor to see if that helps to fix the gas in oil issue.
Please give me ideas to help me fix my issues as stated in original post. Thank you.