(1) I think it is very unlikely that Adams would stay out of the race in 1824 (why? "I've been training for this job all my life, I'm 57 and not getting any younger, the end of the Virginia Dynasty along with the fact there are three southern slaveholders running leaves an opening for a northerner like me--and I won't run!") and somehow win in 1828. In fact, his winning a second minority victory in 1828, while also unlikely, seems more plausible:
https://www.alternatehistory.com/discussion/showthread.php?t=299545
(2) We often mistakenly think that because he was a nationalist, Adams must have been a protectionist like Clay. Actually, Adams held moderate views on the tariff, and the Tariff of Abominations was nor his work:
"Henry Clay's ardor in support of protective tariffs was well known, but there was considerable uncertainty regarding Adams's views. His New England constituency was divided between long-standing concern for promotion of foreign commerce and newly developing interest in protection of domestic industry. A further complication was the fact that administration supporters had lost control of Congress in the election of 1826. Senator Martin Van Buren had supported William H. Crawford for the presidency in 1824, opposed Adams's election, and remained hostile to the administration throughout Adams's tenure. Recognizing the divisions that marked the Adams administration's position on the tariff, Van Buren led a campaign designed to set high tariffs to protect mid-Atlantic and western agricultural interests—levies on raw wool, flax, molasses, hemp, and distilled spirits. In the end, Congress forced Adams to accept a stricter tariff than he would have preferred by refusing to consider more moderate proposals. Adams had to choose between a stringently protective tariff or no tariff at all, and Adams accepted the former."
http://millercenter.org/president/jqadams/essays/biography/4
(3) Presumably he would try to solve the problem the way Jackson did--with a mixture of compromise on the tariff with threats of force. But he would probably have a harder time getting congressional support...