The glow plugs are fine.

If you floor the accelerator during cranking????

The new variable is the fuel. It may have loosened all the old deposits
and dumped them into the fuel filters.

Focus on the fuel side, look at the small clear filter - the clear
plastic one - replace it if it's dark, OK if it still looks like wet
redwood. If you need to replace the one filter replace the spin on
filter as well.

Look at the clear plastic fuel lines - any air bubbles?? If so there's
an air leak probably at a hose to fuel line joint or a filter or the
hand primer pump's top "O" ring is shot and the hand pump needs to be
replaced - $20.

If you find nothing pull the vacuum line off the shut down bellows. That
connection is at the aft end of the injection pump - between the IP and
oil filter housing. If that's the cause you'll need to shut down the
motor using the throttle linkage STOP lever until the shut down device
is replaced.

Finally, take a deep breath, remove the valve cover and check the
timing. Turn the motor pulling and pushing on the drive belts until a
notch in the thrust collar immediately behind the cam's chain sprocket
is exactly aligned with a groove cut into the driver side front cam
support (cam centerline). Rotate the motor only rightward, clockwise.
When the notch is aligned with the groove the cam is at its 00 degrees,
then read the crankshaft angle from the pointer above the harmonic
balancer. It should not exceed 5 degrees, but probably will be at 7
degrees or so. Above 5 is the time to replace the timing chain anyway.

I suspect if there's no fuel problem that the chain may have jumped a
tooth or two on the sprocket and that the cam is no longer in sync with
the crank. The injection pump is driven by the same chain so the
injection will also be "off". This is the dire news side of the
suggestion I'd focus first on the filters, particularly if you've run
Bio100 fuel in the car. Always look at the simple things first.

Well, you tested all the bits separately but did you
pull a glow plug, turn the key on and see if it heats
up? That is if the whole system works together?