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

andy
September 2012