not cutting gas

Hello, I have a question related to my problem. My vehicle is 307 1.6 xt premium. Lpg is available. 2003 model. When I press the drain to change gear or stop while my vehicle is in use, the accelerator pedal remains in the position for 3 to 4 seconds as if it was still pressed, then the tachometer drops very slowly. Why do you think this is due to? I brought a few masters and they couldn't solve it. They said that we can not solve them, especially in ford model vehicles. I would be glad if someone who has knowledge or who has come to help can help
Fatih KARADUMAN
ESKISEHIR

Get a pedal test from PP2000.

I do butterfly cleaning and adaptation. If it is not resolved, I will have the pedal test, but one of the masters I have brought has done a few tests before. It changed the flow sensor or something, but we couldn't reach the solution