I have a issue with my 2002 Volvo v70XC 2.4T. The car has a LPG installation. I start it cold and run it in gasoline and there is no faults. After running it at high RPM the moment I bring it down to a lower RMP injector 4 begins to misfire. I don't think its the injector because it runs well, I think it could be wiring that heats up and starts to misfire. In LPG there are no issues. As a extra note, I am due to chase the lambda sensor that is bad.

Can anyone tell me if they have ad any issue like this before, and how they solved it? Thanks