I have a ’91 Honda Civic hatchback with a D15B1. It has a new head, head gasket, and radiator. The car will start up and run great, but if you turn it off, it may or may not start back up. If it does, it runs like trash—spitting and sputtering. I’m just trying to diagnose what’s going on. I’ve heard it could be the intake, the main relay, or maybe even water in the gas.

 

Out of curiosity, have you pulled the spark plugs to look at them? Also, do you have a borescope that you can look inside the cylinder after you pull the spark plug?