no start after sitting

Could be simple as linkage adjustment. With OEM shifters, park is where it is. dont take much to loose that. Shifters neutral gate usually has enough wiggle in it to find a sweet spot. Hold the key in start position while moving the shifter. If adjustment is the problem, the relay should click at some point.
May not be adjustment. If the NSS switch is worn, leaking fluid into connections will come and go.
Years ago My bro-in-law ( RIP catfish ) had same issue with his chevy pick up. Most times it would start, once in a while he would have to push the thing away from the gas pumps because it wouldn't start until it decided to. I found the signal wire from switch to starter cut and pieced in 3 places, household wire nut at one, loose tape at another, corroded green wires twisted together. I cured it.
You could put a ohms meter on the brown wire at starter relay. You want very close to zero resistance in park and neutral at every repeated test.