Omage A 3.0 24V many small problems

Hello together, since yesterday I have a 91er Omage Caravan with 3.0 24V engine. Unfortunately there are some problems that have never disturbed the previous owner and which I would have cleaned up. 1. The electric sunroof only goes up and not back. I just took off the panel and tried to turn the engine by hand with a screwdriver, but it also went only to the position where the engine always shuts down. What can that be, how can I get the part back to work? 2. The left front electric window lift stops after 2/3 and drives back a little bit. Only if I hold this small button close to the switch at the same time it works. 3. The digital clock on the on-board computer often simply stops and thus the clock constantly follows? What is that? 4. The motor sometimes starts to stutter when accelerating, for example like a power hole, it then pulls something, and then someone’s an idea? 5. – X. There’s certainly more to it that I notice in the course of time, but actually the car is really great.. Thank you for your answers, in advance.. Hendrik