[MT-2500]

Yes the injectors are separate but are under the upper intake in a big black case.
First Have you checked the fuel filter?
Then.
You need to run a full fuel pressure check on it.
It requires 65-66 lbs of fuel pressure on a cold start.
59 is not quite enough. Even 2-3 lbs low will give a hard start cold.
Make sure your gauge is up to par and reading good.
Here is the guide lines on a fuel pressure check.
And it will let you know if fuel pump is weak or if fuel pressure regulator is leaking or bad.
Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
Post back fuel pressure readings.