HI,
In theory if you set the satic timing(engine not running to the engine casing
marks approx 12deg, btdc, AND the rotor arm is pointing to no1 in the distributor position, then the ECU RUNS it from there, the dissy has a
in lay mans terms a switch inside it for a signal to the ecu so with the vacuum pipe
connected to the ECU AND inlet manifold the ecu knows what load is on the engine,
as we have said earlier about the vacuum pipe not being kinked or squashed
before it connects to the ecu, pull the pipe off the inlet manifold stub and blow
down it to see if it is clear remove it off ecu watch you dont snap the union
on the ecu, if all seems good at that end, check with the same pipe back on the manifold and try and blow into the manifold,COULD be partly blocked inside the
manifold causing a varied reading to the ECU load, also check the stub is sercurer on the manifold, Cant think of anything else
as all faults seem covered,

DAVE R.