leyland daf starting problems?

hi i have leyland daf 150 sometimes it starts fine you can start from cold and it will start go down road a mile get out to go shop get back in and it swings and swings and takes a while to start drove 2 hours in it at weekend parked up turned off and on again and started fine got out and realised i needed to realign got in and same agen took ages to start checked for leaks no leaks in fuel line any help will do thank you so much