In 1987, after 10 years away from the ring, Foreman surprised the boxing world by announcing a comeback at the age of 38. In his autobiography, he wrote that his primary motive was to raise money to fund the youth center he had created, which had required much of the money he had earned in the initial phase of his career. Another stated ambition was to fight Mike Tyson. For his first fight, he went to Sacramento, California, where he beat journeyman Steve Zouski by a knockout in four rounds. Foreman weighed 267 lb (121 kg) for the fight and looked badly out of shape. Although many thought his decision to return to the ring was a mistake, Foreman countered that he had returned to prove that age was not a barrier to people achieving their goals (as he said later, he wanted to show that age 40 is not a "death sentence"). He won four more bouts that year, gradually slimming down and improving his fitness. In 1988, he won nine times. Perhaps his most notable win during this period was a seventh-round knockout of former Light Heavyweight and Cruiserweight Champion Dwight Muhammad Qawi.  Having always been a deliberate fighter, Foreman had not lost much mobility in the ring since his first "retirement", although he found it harder to keep his balance after throwing big punches and could no longer throw rapid combinations. He was still capable of landing heavy single blows, however. The late-round fatigue that had plagued him in the ring as a young man now seemed to be unexpectedly gone, and he could comfortably compete for 12 rounds. Foreman attributed this to his new, relaxed fighting style (he has spoken of how, earlier in his career, his lack of stamina came from an enormous amount of nervous tension).  By 1989, while continuing his comeback, Foreman had sold his name and face for the advertising of various products, selling everything from grills to mufflers on TV. For this purpose his public persona was reinvented, and the formerly aloof, ominous Foreman had been replaced by a smiling, friendly George. He and Ali had become friends, and he followed in Ali's footsteps by making himself a celebrity outside the boundaries of boxing.  Foreman continued his string of victories, winning five more fights, the most impressive being a three-round win over Bert Cooper, who went on to contest the Undisputed Heavyweight title against Evander Holyfield.

Answer this question "When was his second comeback?" by extracting the answer from the text above.
Foreman surprised the boxing world by announcing a comeback at the age of 38.