Hey there, so, I've acquired a 91 pickup from an acquaintance of mine and I've found that there connectors that don't seem to go anywhere, and blocked off vacuum tube connector. I'm pretty new to truck maintenance and repairs, and while I've now done a small amount of work on a couple of parts (removed the throttle body, cleaned it, adjusted TPS, installed after market tachometer) I'm still not entirely sure what the stock version of my engine is supposed to look like.

Because of this it's very hard for me to tell what is and isn't supposed to be connected, and to that end, I've found a few things that seem odd to me, or purposeless and so I was hoping someone here might be able to tell me what they're actually supposed to be connected to if anything.

I've looked online for wiring diagrams but those tend to be a little outside of what I can comfortably understand, and something like a detailed picture of my trucks engine bay with everything labelled doesn't seem to exist. Regardless, the components in question are the following:

1. A vacuum tube hookup that is purposely blocked.
2. A wire and connector coming from the cab on the drive side wheel well, coming through the firewall that's not connected to anything.
3. A connector and wire that was tucked away in the wires that appear to be coming from the intake manifold towards the engine.
4. A weird 3 pronged connector for a vacuum tube connector at the rear of the intake, with one of the 3 prongs being purposely blocked.

Overall, the truck doesn't run perfectly and I'm still diagnosing a bunch of problems, the current list is:

Throws code 42
"VEHICLE SPEED SENSOR SIGNAL CIRCUIT--NO SPD. SIGNAL FOR SEVERAL SECONDS
WHILE VEHICLE IS OPERATED UNDER HEAVY LOAD (TPS/MAP/AIR FLOW INPUTS)
--SPEED SENSOR/CIRCUIT
--ECU"

Has a very high idle~2000RPM on cold start, which slowly decreases down to normal idle RPM after driving for a while.

Poor gas mileage, which I assume is possibly just a symptom of the terrible idle that I'm running.

But for now, I'd settle for just knowing what these components are supposed to do/be connected to.

 

#4 is the "Gas Connector", whose 3 ports all just provide vacuum. On the 3VZE, those 3 ports can go to the PAIR, Fuel Pressure-up, A/C idle-up, Cruise Control, and Automatic Differential Disconnect. If you don't have 4wd, A/C, or Cruise, then the extra port is factory-blocked with a fitting like you have.

I will have to leave the first 3 to those who actually know something about the 22re