UK Car Repair: Jaguar exhaust smells, air flow meter, o2 sensor

Question
Just got a 1987 Jag xj6 new engine, but exhaust smells real strong on fuel and idle is up and down. Could it be the O2 sensor?
Randall Nevis

Answer
It seemms to be running too rich, It is most likely the Air flow meter in the inlet system although, it may be too high fuel pressure.  The AFM is tricky to adjust and you need gauges to check the pressure.  The person who rebuilt the engine (or any competent garage)should be able to test it.