A respiratory problem has forced Merle Haggard to cancel a string of tour dates in Texas, Arkansas and New Mexico, according to the tour page of his official Web site. Haggard’s three early October dates in Texas could be his last concerts of 2004. The Texas shows include an Oct. 2 performance with Willie Nelson at the Cattle Baron’s Ball. The Dallas show benefits the American Cancer Society. Haggard, 67, is working on a new album with producer Jimmy Bowen to be released on Capitol Records Nashville next year.