Had exact same issue, got car back late last night. Was the ignition module. Have splitfires and they were fine, block is only producing 2/3rd of rated power (built for) - compression all good. Checked vacuum hoses etc, cables etc. Thought it may have been the 040, but it primed for the 3-5 seconds once ignition on.
So would say check AFM, if not AFM get ignition module checked pending the plugs have been changed/gapped etc.