By Asif Shahzad and Syed Raza Hassan ISLAMABAD (Reuters) -Pakistan’s Prime Minister Imran Khan was ousted on Sunday when he lost a vote of confidence in parliament, after being deserted by coalition partners who blame him for a crumbling economy and failure to deliver on his campaign promises. The result of the vote, which was the culmination of a 13-hour session that included repeated delays, was announced just before 0100 (2000 GMT on Saturday) by the presiding speaker of parliament’s lower house, Ayaz Sadiq. Khan, 69 was ousted after 3-1/2 years as leader of the nuclear-armed country of 220…