The bulls of the Dow Jones Industrial Index took a deep breath yesterday with a 147 point gasp. But it was a rare one. Over the last 28 trading days, including all of April and May so far, the index declined only four days. If today’s trend continues, the Dow will close up enough for a flat finish for the week saving the five-week streak. Mega corporate buyouts, potential for a Fed rate cut, reasonable stock valuations and old fashioned-momentum are propelling the averages.