Recreational Vehicle Lpg Tank Valve/gauge problems of the 2017 Nissan Pathfinder

We purchased a 2017 Nissan Pathfinder for our family 5 from peters Nissan in nashua n. H. August 2017. In November 2018 we started having problems with the vehicle losing power, and shaking like it's ready to stall out. We took it in to Nissan and they claimed they replaced all 6 fuel injectors and 5 upper injector 0-rings. We brought it back on Dec 3, 2018 for the same problem and Nissan documentation states that they performed road test and vehicle road gauge read all the way empty even though the vehicle had one half a tank of fuel. They claimed to have replaced internal fuel pump and and the vehicle fuel gauge was then reading at the appropriate level and the vehicle was returned to us. On Jan 14, 2019 we took the vehicle back to Nissan for the same mechanical problem and they kept it until Feb 6 claiming that they were doing extensive research to diagnose and fix the problem. After 3 weeks without our vehicle we were called to pick it up and the work order stated �road tested vehicle and could not duplicate condition�. However the paperwork indicates that the mileage in was 23181 and the mileage out was exactly the same, 23181, indicating that Nissan never really did anything to resolve the problem. We are a family of 5 and for us this vehicle was a huge investment, we're confident in the Nissan brand name but now we are regretting our decision. We have requested that Nissan buy the vehicle back so we can purchase a reliable vehicle from another brand name corporation or at a minimum replace this vehicle with a new Nissan Pathfinder to no avail, so now we feel we are stuck with this high priced lemon.