Extra random injector firings

I currently have a client's XJS that has an intermittent issue I'm seeking help with.
Lucas 3CU is 83477B
The car was parked up 8 years ago because of this problem. Now trying to recommission.
Owner's complaint = Drives OK for 1 hour or so, then cuts out and won't restart for some time.
I experienced this in the workshop and positively determined that the cutting out is flooding due to additional injector firings. Once stalled, the injectors would continue to randomly fire.
My first suspicion was trigger board or throttle sensor / trigger. I rigged the oscilloscope to test these. The acceleration sweep 10 firings still work OK and no extras from there. I tried to test the distributor trigger, but could not repeat the symptom.
I opened the distributor to inspect and found the board very cooked (I've seen many that look cooked but this by far the worst)
I've replaced the trigger board with the Hall effect unit currently recommended. Run it up and after warming, the symptom returned.
Tomorrow I shall be scoping the output channels directly from the ECU but I can't imagine anywhere else the extra, random pulses could come from.
What voltage pulse should I expect on pin 25?
Any other clues as to what could cause this?

...would be very nice if you could introduce yourself and sign with your Name !

Hi unknown,

can you please remove throttle switch connector and try without that. If that does not help, you must use a scope to monitor trigger board pulses and ECU pulses to amplifier and finally also amplifier to injectors. Pin 25 has 12V signals.

Hi,
I had suspected the trigger board as you did.

Can you try another ECU?

Regards
Norbert

Sorry. I just copied & pasted from an earlier email.
I am Ian Munford.
Jaguar specialist tech in Auckland NZ

I have another ECU that had been labelled "Faulty"
Most recent tests with both ECU's worked fine and symptom not present to test.
I'm now suspecting main relay contacts or power/ground connection but as symptom is elusive, I can't prove anything.