Starting difficulties

Hello!

After the engine was rebuilt at the beginning of this year, I got through well. A couple of heat problems in the summer, who doesn't know this, but otherwise everything went well, the car ran.

However, I have had a problem with the start for a few weeks. It starts immediately, turns short high to just under 1000 as always and then loses rapidly at speed and goes out or almost out. When he's still on, he's very restless. If I have kept him alive (with a kick on the gas), then he's shaking for a while.

Since I'm not very knowledgeable about the technology of the "little one", I would like to have an idea before I go to the workshop so that they don't search forever and make it more expensive than it is anyway.

So, does anyone know that, does anyone have an idea of what it might be? I am grateful for every help, because this is not the way to go. Every time I take off, I think it's the last one.

Thanks already, greeting Sebastian