1998 Chevy Camaro Don't know what the problem is - need hel

Don't know if electrical, just didn't know what to put in category. My car won't start at times. No rhyme or reason. Sometimes cold, sometimes hot. Doesn't make a difference. Still starts at times and not at others. Sometimes won't start a whole day, then the next morning, starts right up. Sometimes starts all day, then later in the day won't. I usually play with it for a while by waiting seconds then trying to start again. Sometimes starts the second time sometimes the 12 times and so on. I had two mechanic shops look at it, one was a Chevrolet dealership. The other had a mechanic of 20 years that could not figure it out. No can fix. It turns over but doesn't start. No lights indicate problem. No check engline light. They've change a hornest, the ignition switch, starter sensor, some other sensor, a module and non of these worked. After they tried to fix it would work great for about two days, then go right back to not starting. Any suggestions.