Newbie here guys...big hello from Doncaster

Finally got my fault code read; 1. Lamdba sensor left bank fault. 2. Miss fires to 4 of the 8 cylinders. the guy resent the engine management and reccomended i switch off the LPG over to petrol see if they come back on, if they do he said replace Lamdba sensor, core plugs to the 4 miss fire...

4.4 V8 2004 .....Basicly my EMS light on and shes running a little rough she's down on tork and and not very responsive dont kick down easily holds in the gears also i had TRANS OVERHEATING come up on the dash yesterday and if you drive it heavy the EMS light flashers breifly. Im looking for...