Ok, check this out.... First, do you have a toyota oil filter on your engine? the factory oil filters have a check valve in them that keep oil in the passage to the timing chain tensioner... it is a little known secret that the timing chain tensioner is opperated by oil pressure.... if you are running a cheap oil filter, it probably does not run a check valve in it. therefore, the timing chain will flop around until oil pressure can build and the tensioner will come into play.

hope this helps...