HELP 93 Chrysler Concorde idles fine then runs rough

Darn car (http://www.carforums.net/showthread.php?t=34609#) starts and idles fine. Hit about 30mph and it starts running rough. Coughing , etc. then runs smooth and then starts running rough again. The engine light comes on and then the cruise control light and they alternate back and forth. The computer said its the timing belt but not sure because it idles and starts fine and then starts sputtering. Anyone else had this happen or know what it may be. Thanks for any info.