Help!Be crazy with Omega 2.5 V6

Hello dear Schraubergemeinde! I have to report to you again, my last thread was already about my Omi but I have a new problem that I prefer to explain in an extra topic. As in the first thread already mentioned I had read out the error memory and changed on it also the Lima. the whole time now no problem except that the ange shows with “Brembelag”. I have not renewed the contacts yet, think also does not matter with the following Problem. So, well, Tacheles….. This morning the good one jumped in perfect, woman and child packed in the car and drove to the bank. Until here everything was great! I waited in the car and had let him run because the little one slept. Directly afterwards we drove shopping. Omi with radio locked and into the shop. goods were about 30 minutes away. When we came back and everything had been stowed away we wanted to start. The Omi jumped on but immediately went out again! I certainly played the game. Four to six times done. The funny thing is that he runs “normal” when you give gas, you let the accelerator pedal go it drops down to 500 rpm if not even lower and goes out. So I tried to give gas so about 1200 rpm and start driving. That also went, during the drive everything was relatively normal. Only he doesn’t quite have the power as usual. Did I have to brake it out again, unless I switched on Neutral and gave gas. Be still crazy. What should that be? again??? Can someone help me?!? I’ve jammed it off the battery and recharge the battery because it was only half filled after a check…. So, will you look again if cables or the like are off. Thanks for your tips.