1998 Honda Civic My 98 Honda Civic doesn't start consistent

Engine Mechanical problem
1998 Honda Civic 4 cyl Front Wheel Drive 130000 miles

1 month ago, I was having trouble getting my car started. It would turn over, but it wouldn't catch. I would have to keep on the ignition and after almost flooding the car out, it would eventually catch and start. Once it starts, it runs fine. I took it to a mechanic, and he replaced the main relay, thinking that was the problem. 1 week later, it did the same thing, it randomly didn't start in the middle of the day. I took it to a diagnostic mechanic, and he stated it could 1 of many things. So one by one I started replacing those things. Mostly it was a tune up. I've replaced the distributor cap, the spark plugs, and the rotor, and also the fuel filter. One month later, my car is still having problems consistently starting It seems to start OK in the morning and in the evening, but if I have a lot of errands to run throughout the day, and there is a lot of stop and go, then it has a hard time consistently starting every time. Question- What is wrong with my car?