Not sure what's causing this, not a clue really.
On my '76 242...
When I let my car sit for a couple hours, it becomes hard to start. It will turn over but won't fire for two to three seconds. When I let sit over night, it may take seven to ten seconds to kick over while giving it some gas and when it does kick over it won't fire on all cylinders for a few seconds then idle speed will stabilize. For about thirty seconds after idle speed is reached and I give the car a little gas it won't fire for a couple cylinders, and then jump up.

Not a clue what causes the inability to fire after sitting for a while, could there be pressure loss/leaks in my fuel delivery?

 

Fuel Pressure Regulator. Easy to replace and fairly cheap. This would be the first thing to try. I had the same problem with my 93 and that fixed it. Look for the post n here that says "Hard starting 24 Cant Figure It out.