HI,

If the wiring is ok, its either the dizzy, or ecu, as if everything is
working as it should the ecu senses vacuum from the inlet manifold
which is translated by the ecu (internal transducer)

takes engine speed from the dizzy (trigger pulse's)
and from temperature signals gives the correct spark including dwell
angle, the ecu also controls boost and retards the ignition timing
if air temp etc to high, so is really wiring, coil, dizzy, ecu.
if it turns out you need a ecu is it s1 or s2 as i have std ecu's
and what year, i also have a as new the internals for the dizzy,
easy fit just a couple of srew's, mine is available as i have cosworth
management,

DAVE R.