Hi. I have a problem with my mates car. It will start and run fine in the mornings but if you leave it for 5 mins and come back it then wont start for a few hours or sometimes has to be left over night. It doesnt even seem the make any difference how long it runs either. Could be a couple mins or an hour. If I leave it for a bit it wont start again. Ive been doing work on my own cars and for friends and family for years so im fairly competent but I cant work this out. Ive done all the usual checks and cant see anything obviously wrong with it. Can anybody help?*