For Yugoslavia money was always an issue, country went technical bancrupcy in 1982. and was in economical (and any other) decline in the 1980s. That is why it's kept using 2nd generation MiG-21 until 1987. when everyone in the east already had MiG-23 or F-16, Mirage, SAAB 37 or some other 3rd/4th ge...
F-5 Tiger II was seriously evaluated in summer of 1980. Test pilot Suad Hamzić praised the aircraft but decision was to get more MiG-21bis, last one in 1983. Branko Bilbija tested both Mirage-2000 and MiG-29 in 1986. and was in favor of MiG. F-16 was flown by Air Force commander himself in 1990.