Question about plugs in the engine compartment and old Essi problem

Hello, I’m quite new here on the Essi board. Was before on the Astra board. Drive now since mid-April an Escort Mk 7 Gal 1.4l tournament year 96 with 75hp. At first everything was ok only then it started. How should it be different with an Essi? It goes out in the warm condition. Since I am no one who writes immediately, I have read all the topics about this matter for a good week. I have done since the following:Let error codes read——No error codeLLRV cleaned only then exchanged—— error remainsL MM changed—– error remainsZündkerzen changed—– error remainsZündkabel changed—— error remainsAir filter changed—– error remainsControl unit changed——- engine did not run because of a roadblock, so old again inside. 🙁 So I continued to search and discovered the following. A loose plug(red circle) Purple/Black cable and is attached to the wire harness that goes to the ignition coil and an oxidized plug(yellow circle). Where does the one plug belong and for what is the part with the oxidized plug? Then I noticed that when I got the car it was almost empty. I then filled it and shortly afterwards it started then was 3 days rest(tank almost empty) and Sunday evening I filled up again and since Monday it is again. Thank you already Michael