Actually you have a Communist CARB emissions issue... The OEM's experimented on (you) CA's early emissions by releasing emissions in CA first and then the next model year would get the updated emissions for everyone else (Federal Emissions.)
Big question: do you still have to pass emissions with it?
No? - Remove SES lamp, plug EGR vac line, Plug off EPR vac line. Use any vac pump that will fit.
Note: TCC lock up, if you have it, may be controlled by this computer.
Yes:
So your 1984 IS a 1984, but a CA emissions 1984. Hopefully using 1985 parts (Looks like it was used up to and on 1989 R/V series as well) will help otherwise you got to match part numbers and last resort at a GM dealer parts counter. Best I can tell is the primitive emissions computer info is rare to find. It controls the EGR and EPR, Exhaust Pressure Regulator, only. The EPR is a valve on the driver's side manifold that flows exhaust through the intake to heat it up and possibly flow more EGR.
Your best way to tell is a lack of a Service Engine Soon bulb on the other rides. This bulb is a separate add in assembly on the lower left of the dash.
Last time I ran into this was an electronic EGR valve on a 1993 4.3L TBI CA emissions pickup outside of CA. 1993 Federal emissions everywhere else was vacuum controlled. It took two weeks to get the GM part and it was $150 more than the vac controlled part. Only 1994 would show the correct part at the Colorado dealer.
