Jaguar Repair: 1984 XJS idles then dies, vacuum leaks, vacuum hoses

Question
1984 Jaguar XJS wouldn't start after sitting for 3 years.  After establishing spark (replaced module, cleaned connections) engine started, but wouldn't run faster than a slow (estimated 200 rpm) idle.

Fixed vacuum hoses/leaks, checked throttle pot (good), all injectors operating, all plugs firing, but no change.

Dies if throttle opened, and after 2 minutes idling will start to oscillate between faster and slower speed until stalling altogether with no startup possible (will "catch" but stall) until after some time at all

If left intake blocked, runs better - no discernible air flow through right intake.  Sometimes seems to run on all 12 other times not.  Shouldn't there be approximately equal flow in both intakes?

Answer
Hi Andy,
Yes, both should pull the same amount of air.

You need to pull a compression test on all 12 cylinders to see that the engine is ok then check manifold vacuum on both A and B bank (throttles closed)
Check fuel pressure and use a "Noid" light on each injection wire. If you don't have one most auto parts suppliers have them and the one for the Bosch "L" Jetronic system is the same plug as the "Lucas".
Check for a vacuum leaks on both banks too.
Howard