Iron Man (1968 series) #280

Having returned from Operation Galactic Storm, Iron Man (Tony Stark) is in a gloomy mood, brooding over his deteriorating health and wishing he had died in space. James Rhodes tries to cheer him up, to be more optimistic but Tony has had it, punching a mirror out of frustration...

...and at this point he is pulled out of his time stream and looking around, he sees a crowd of purple skinned aliens saluting him. He passes out...and when he awakens he is told he is in the 28th century. The leader, Sysop, explains that they need his help to overcome an impending disaster—and they are The Stark, and Tony is their progenitor, their patron, their god.... Brief history: they were a primitive tribe until a Stark spacecraft crashed on their world and then in a single generation they built a high-tech civilization and a priesthood called the Programmers oversaw their development. But now war, crime, and ecological disaster threaten their world—and they are under attack by barbarians. And so Tony Stark is their only hope for salvation. Tony is shocked that they sincerely believe he can help them and excuses himself. He broods, fusses, yells but he still feels at least partly responsible for The Stark's disaster—so he begins designing all sort of improvements to clean up the environment and more. But the barbarians invade the sanctuary and Iron Man goes out to fight them—but Sysop stops him, telling Tony that he must be returned to his own time, lest his death here cause a chronic rift. With his dying act, Sysop sends Tony back...

...to milliseconds after his disappearance so that Rhodey doesn't even realize he had gone. Then Iron Man collapses to the floor....