Hey people, I have this problem

Hey, my Essi BJ 96 with 75 hp doesn’t really pull anymore(i.e. that’s almost finished at 140 had an engine damage before and the engine went without problems 190 KM/H), runs in the stand very restless so jerks and above all he has a much higher fuel consumption. please help me what possibilities there are for improvement. until then many thanks I’m really stunned until then lg steve