Hard starting 87 300TD

[KansasDiesel]

Trying to figure this problem out, and need help.
This car has started in cold weather down to single digits. Starts better when plugged in. But last week all of the sudden it wouldn't start even plugged in unless I cranked several times for a long time. First I figured I had some glow plugs out, changed 5 glow plugs and couldn't get the #1 out ( different story but need advice to remove a stuck glow plug too) Out of the ones I replaced they seemed to all have the right resistance. Started right up ( in the garage ) that next day leaving for work same thing cranked forever to get it started. Removed and cleaned all the injectors. Ran the smoothest it had since I bought the car last October. Drove it all day, that night same thing cranked forever before it started.
It starts fine after it warms up. It is warmer here right now, but I need this to be a dependable car.

Any help? Any ideas?

Thanks