89 6.2 - slow start

[Electricduane]

hi:

My 6.2 all of a sudden began acting up. When started cold, it is hard to start, runs rough, and usually dies after it does start. I crank it, mash the pedal, then can get it going. Once it's warm, it runs fine and starts up again easily.

This just started. I have owned the vehicle a year or so, it was fine before.

It's now about 80 during the day here (Northern CA), when the "slow start" thing has occurred. So not a real cold start by any stretch.

-It has the glow plug mod, light comes on and Ford solenoid "clanks" indicating GPs are functioning.

-It has brand new Bosch Duraterm glow plugs. I hold the button for 10-11 seconds. Good long glow. I tested the plugs, they light up correctly.

WILD CARD: Vehicle previously had a "veggie oil" kit on it, but I have run many tanks of regular diesel through it, should have purged all veggie oil out of it.

MY GUESSES:

1) Sock on fuel tank sender is clogging up, cold engine is starving for fuel.
2) Issue with 1 or more injectors?

DOUBTFUL:
1) Air leak in fuel line should not correct itself when engine warms up. ??
2) Dying lift pump also would not correct itself when engine warms up. ??