You may try some power service conditioner with a few tanks. Its usually a good thing to run on a regular basis to keep the injectors and pump lubricated better, as well as keeping the diesel conditioned. As far as smoking the way you were talking it sounds like its making ALOT of very black dense smoke, if so, then no its NOT supposed to do that. It would smoke some under a heavy load, but not profusely. I looked at buying a 94 IDI like yours and unloaded it would never smoke. While pulling a load it didn't make any smoke either. Its possible your injection pump is going south on you. I would take it to a diesel shop (NOT the Ford dealer, unless they deal in alot of diesels and large trucks) and have them inspect the pump. I would also have them do a compression test on each cylinder. Its possible that the rings are getting worn out and you're not getting enough compression to fully ignite the fuel causing the overfuelling conditions that you're experiencing.