Start problems with the 930 (911 Turbo 3.3 300 hp) from 1987

Hello together, I have a little problem with which you might be able to help me: If my 911 Turbo (from 1987 with 150,000km) is over the winter for a few months it starts right after the first start attempt after hardly a few turns. If it is warm and only a few minutes out, it starts again immediately. But if it stands more than 30 minutes (1, 2, 3… etc. hours or days) up to one week!, then it always takes a long time to jump on and even a nige powerful accelerator pressures to run around. But if it is then again longer than a week, it starts immediately again. Complete engine service was made with spark plugs and everything drumm and ramm What can that be? Sunny he runs very well and round. I hope someone already had the problem and found the cause of the problem. Many thanks in advance and friendly greetings Joeri (that’s what “Juri” says)