1994 Jaguar XJS Engine Hesitation

Picked up car from recent repair on Engine Mounts. When drove out of shop, engine sputtered and stalled. Engine had been previously perfect and clean. OBD says Fuel system code 12 and then 89. Tried crank sensor and vacuum purge valve. Still not it. Possibly the air flow meter. Awaiting part to substitute. Total lack of compression. Smell of un-fully burnt gas out of exhaust

Highly Puzzling. Can you help?