Terrorism and violence rather than peaceful diplomacy. How far would you agree with this view of the activities of the PLO in the Middle East in the period 1973 to 1995?

I agree with this view. It was in 1964, when the Arab League set up Palestine Liberation Organisation (PLO) and Palestine Liberation Army under Ahmad Shukeiri. Till 1974, most of the activities of PLO were confined to Guerrilla attacks and indeed were acts of terrorism; and the given statement fits for this period. For example, after the six day war in 1967, PLO demanded more actions from Arab countries against Israel. When not substantial happened, the Popular Front for the Liberation of Palestine (PFLA) of the PLO embarked the series of terrorist attacks to attract worldwide attention. Between 1970s and 1980s, the PLO and other armed Palestinian groups kept themselves engaged in terrorist activities such as airline hijacking; killing Israeli soldiers, civilians and officials. In 1972, the Palestinian Black September gunmen took the Israeli team hostage at the Munich Olympics and killed several of its team members. Only after this event, Israel launched a series of hard steps including assassination of Palestinians. In 1973, Israel raided PLO bases in Beirut and Southern Lebanon during the October Yom Kippur / Ramadan war.
Meanwhile, the PLFA and PLO appeared to have took separate routes and Arab League recognized PLO as sole representative of Palestine People. Its leader Yasser Arafat became the first non-state leader to address the UNGA in 1974 with his famous “olive branch… and freedom fighter’s gun” speech. Things appeared to improve with Israel pledge to set up Palestinian self government in West Bank and Gaza (as part of Camp David Accords). However, the terrorist activities continued for decades. In 1982, when Israeli invaded Lebanon and occupied it, PLO had to relocate to Tunisia. This was followed by massacres in Palestine; Israeli airstrikes; First Intifada (uprising); rise of Hamas Movement etc.
In 1992, the Israeli Labour government started secret talks with PLO and Oslo Accords were signed in 1993. Israel withdrew from most of Gaza and West Bank and Yasse Arafat was allowed to move his PLO administration from Tunis and set up the Palestinian National Authority. In 1995, an Interim Agreement set out path for transfer of further power and territory to Palestinian National Authority. The above description of the activities makes it clear that terrorism than peaceful diplomacy had dominated the scene between 1973 to 1995.