Start problems after long journey

Hello together, I have a problem with my Saab 900 S, built in 1992, and hope that someone might have an idea what it might be. Basically, the car always starts without problems, whether it has outside -5°C or has stood for several days. The problem only occurs under a certain condition: If I have driven a longer distance (e.g. highway) and the car has then stopped for 4–5 hours, it does not start any more. The starter spins quite normally, but the mo tor feels “dead” as if the ignition is not coming. But pushing helps – then it starts immediately! Another detail: The tachometer moves slightly during the start attempt, but stays low. If this is relevant: the battery is fine, and the starter has been renewed recently. Has anyone ever had a similar problem or an idea, which I should test first? I am grateful for every tip! Many greetings