Tempra sometimes doesn’t fight

hi. have a problem with my old tempra. since a good year the car does not start about once a week. often it works after three to five try, but recently only after 1.5 std. whether it starts or not is independent of the weather, temperature etc. usually however when I have driven a short distance to shop/refuel, or when the sun has appeared on the bonnet. (?!?) in the start attempts the starter runs and the rest also sounds normal, except that e r just doesn’t start – until he suddenly does it. battery, spark plugs, gasoline pump and an empty-running motörchen (?) I have already replaced. would be great if someone had tips for me, what I can still do, because the gentlemen in the workshop don’t really know any more. thank you + hello.