check your injector pump type also as some require that you wire the throttle open full and some do not.
On mine the IP has no butterfly inthe intake so no need to wire the throttle open.
this could affect your readings.......

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'99 S420 - Mommies
'72 280SE 4.5 - looking to breathe life into it
'84 300SD Grey - Sold
'85 300SD Silver - Sold
'78 Ski Nautique