Is it hard to start or does not start at all until you let it sit? I had an issue once where my car would crank, but not start when hot. I'd let it sit for 30min and it would fire right up. It turned out to be a hairline crack in the circuitboard on the ignition module that would expend at a certain temp. I replaced the module and it was good. Like others said if it just cranks a long time before firing the issue may be fuel system related. Do you let the fuel pump prime before trying to start it?