I had a problem with my 91 honda civic dx not starting after driven for awhile. It would crank over but the engine wouldn't start. I soldered the main relay joints and the problem went away.. but when I drive for awhile I hear a loud vibrating noise coming from under the dash by the main relay area but the car still drives fine at 60 mph.. After about 30 seconds the noise goes away but occasionally will come back but doesn't seem to affect the car.. would like to fix this problem eventually but help would be nice? Ps I also called honda and found out my igniter has already been replaced don't know if that will help

Sounds like the ECM may be failing. Be sure to clean the main ECM ground on the thermostat housing. The problem may also be with your resoldered main relay--consider replacing it with a new one.

I don't know if my relay also has something to do with this but sometimes when I stop at a red light it will start to rough idle and then when I try to take off it feels like the car hesitates to move no matter how hard I'm pressing the gas peddle.. feels like I'm shifting wrong but I'm not because I'm completely in gear and just pressing the gas.. whenever I shift out of the gear it goes away like it never happened.. usually its 1st and 2nd gear but I've felt it in 3rd also

Replace the spark plugs (NGK only), if they have not been changed in the last 24,000 miles or 24 months.

Yeah I did that as well with the rotor switch and distributor and wires I have a feeling it has something to do with the solder job.. it's a bummer ill have to buy a new main cause it sucked putting it in