Diesel Doctor

[cierva]

I have a 1983 Nissan sd22 pickup. For the first 5 minutes or so after I start it, it kind of sounds like it skips a beat, maybe like there's air in the fuel system. I don't feel it after a little while of driving it, and at higher RPMs (maybe just not noticeable). Also, it reliably blows out a whole bunch of black smoke when I first start it in the morning, especially if it's cold. And looses power quickly going up hills.
My main concern is the spiking I mentioned first, but advice on making the engine run smoother in general is greatly appreciated.

I have already changed the fuel filter, and when I did that i filled it with "Diesel Purge" to help clean out the engine. I've checked the fuel lines for weak connections and cut & shortened the ends where they where cracking. And I've used the hand primer pump at the fuel injection pump to get any air out of the lines.

Maybe change all the fuel lines in case they are so old that they are corroding inside? or run more Diesel Purge-type cleaner through it again?

Any advice welcome. Thank you.