Time Thieves by Dean Koontz
Peter Mullion woke up in his garage not knowing what had happened to him in the past few weeks. His wife and the doctor think he has amnesia. Yet he feels it's more than amnesia and so he began to search for clues. When he and his wife went out to eat, he saw a man he thought he recognized but he doesn't have a clue where he had seen him. And as he and his wife Della made their way to their resthouse, he began to feel that his mysterious disappearance was somehow connected to his trip there. He began to feel too that he was being watched. He saw the man again at the restaurant watching him from outside his home. Things went from bad to worse as he had an episode of time-space distortion. He could not count and recognize numbers and he did not know where he was supposed to go. The trip to his office became a challenge. He passed out, then when he came to his senses, his wife told him he disappeared again for 3 days. Was the man who had been watching him had something to d...