from what you described, here are my opinion: the LPG system is the first thing I would investigate, especially because the car runs perfectly on petrol and the problem appears after switching to LPG, mainly under heavy acceleration.
The symptom pattern—runs normally for a few kilometres → hard acceleration → jerking/misfire → check-engine light → sometimes disappears after restarting—makes me particularly suspicious of the LPG mixture or gas pressure under load.