No, Raiders and Crusade take place two years apart.

From the opening titles in each film (checked on my DVDs):

Raiders: South America, 1936
Temple of Doom: Shanghai, 1935
Last Crusade: Utah, 1912; Portugese Coast, 1938

I don't know about Crystal Skull outside of the fact that it was set in the fifties, since I don't own the DVD.

And the Temple of Doom prequel/sequel debate ultimately doesn't matter - it's set a year before, yes, but it was clearly meant to be seen after Raiders and not before. It's a sequel. It just happens to be set earlier.