I was at Farnborough that year too; watching the seeminlg endless run-up from the comfort of the GE Chalet, the thing I remember most as it started to move off, was the flash of flame out of the front of the nacelle just before the "Pop" reached us, follewed by a round of applause and much barely-disguised amusement from all the GE folk around me!
The consensus seemed to be that although they had made a passable job of reverse engineering the mechanicals, the FADEC was not up to the task. Apparently all attempts to purchase up to date engine managment systems from western companies, was vetoed by the US Goverment on the grounds that the technology would find its way onto the Blackjack!