Well got the car back from the lexus dealer with a number of codes they still can't pin point the fault so here was what the diagnostic report said
P0171 system to lean (AF lean malfunction bank 1 )
P0300 random/multiple cylinder misfire detected
P0301 cylinder 1 misfire detected
P0302 cylinder 2 misfire detected
P0303 cylinder 3 misfire detected
Can anybody shed a light on this now they are saying it needs further investigation