The third-generation Mustang was produced from 1979 to 1993. Built on Ford’s ubiquitous Fox platform, it evolved through a number of sub-models, trim levels, and drivetrain combinations during its production life.
By 1990, Ford resources began to focus on the next Mustang, due to debut in 1994. There would be few changes in the model line through its retirement in 1993. Most changes would be visual. For 1990, a limited run of 4,103 emerald green exterior, and white leather interior 5.0 LX convertibles were produced for a contest held by 7-Up, but it was cancelled at the last second. For 1991, the 2.3L I4 engines received an increase in horsepower, from 88 to 105, due to a revised cylinder head with two spark plugs per cylinder.
Source: Wikipedia, 2012