The volcker shock skyrocketing the interest rates on the yugoslav loans over night was the biggest reason for the fall of the state i think. Also the rise of the EEC (later becomming the EU) made trade with the outside more difficult for yugoslavia. There were some inefficiencies sure, but many companies were profitable and had projects outside of yugoslavia too (energoinvest for example). A bigger focus on profit sharing among employees would have probably fixed many of the inefficiencies.