By immobiliser, I mean the one fitted in later ECUs that require a Blipper in order to start.
early ECUs as I understand were simple fuel control devices,(Mems) fault readers for early Rover engines are few and far between, never found one to buy.
When starting running / tickover issues arise on the T16 I simply reset the ECU by turning off the main red switch and turning on again
equivalent of turning a computer off at the wall.
Bit simple but worth a try?