Probably a leaky injector or two in my experience.
Turn the key to the position where the fuel pump runs, but the starter does not turn and leave it there for a few seconds before pushing it all the way. If that makes it easier to start, then you are losing pressure in the fuel line and it is likely a leaky injector (could be the check valve/regulator thing).
Next guess would be weak spark from a bad ignition module, silver relay on the way out etc.
*not legal advice*