Smokes black

Hello, my name is Victor, I have a the truck listed above it is aSierra K3500 turbo diesel. There is a problem but, theirs no check engine light indicating that is on is off. I have changed the fuel filter twice. I also add Lucas Oil treatment once then the other time I also add a little of Sea Foam an poured few Oz's as well. Theirs a rough Idle when staring vehicle for about ten to twenty minutes as also exhaust smokes black for about ten to fifteen minutes. Then after ten to twenty minutes the exhaust smoke clears up. If I drive from five to forty five mph while accelerate smoothly rpm's from 750 rpm's to about 1,800 rpm's idle is just little slight rough about if I maintained rpm at if for example 1,500 rpm's it will increase to about 200 to 300 rpm's more then, will drop to about 1,400 rpm's while using the cruse control. If I do force it a little while driving it more quicker the idle will slightly will go up and down. If I drive it for about ten to twenty minutes miles at tops twenties, thirties, forties mph it is running quite okay in that round trip of twenty mile round trip if I go over fifty to fifty five mph idle will get more rough for about the time I am driving it in that trip of twenty miles. There is a small light clicking on the right passenger side of the engine while driving. I think there is a by pass or a failure in injecting more fuel then normal or probably dirty glow plugs and injectors warn out might be or a valve. When I put vehicle park you can smell the diesel burning out of the exhaust when engine is cold while starting it up at any time while smoky black fumes is diesel an there is a small miss fire sound out of the exhaust it sounds like while in idle when gear is in park position. If there is a solution to this situation of having to replace certain part, sensor or adding a certain fluid, treatment, solution or a different adjective to this current problem. I also had this vehicle parked for a few months of ten on I would turn it on an drive it a few several times. It might be that I have had it parked with out driving it more then it so post to be. It might be one of those situations that supposed to operate vehicle more often then usual be before I put it on none operation for tempporary could be who knows.

Please can someone let me know, I will appreciate it a lot very much. Thank you