i have a major head ache that has come into my garage the car in question is a E46 2002 1.8 petrol amd it has had a new engine fitted, same type with no mods, customer took the car away happy two days later the cars back running on two cyclinders so far ive changed the cranksensor, fuel rail, spark plugs, coil pack (which is the complete unit a block of four) done a compression test all cyclinders 14 bar, fuel relay, and diagnostics are showing me nothing any help would be great as im running out od ideas fast.