Elec problems...experts help needed

Headlight problem:

Do you have a multimeter or ohmmeter? If so I would ohm out the wires from the headlight switch to see where they're going. I'm thinking that there's something up with the wiring on the steering column or maybe someone hacked with the wiring at one time and connected the headlights to the starter solenoid (or similar) and now possibly you've got the wire on the other side of the solenoid so it's only hot when you turn the engine over instead of being hot all the time. Those are just guesses...you won't know what's wrong until you get in there and start tracing the wires... an ohm meter will help a lot.

Lower intake sensors:
On a 90 you should have the ACT (Air Charge Temp) sensor towards the firewall side of the lower intake, the fan motor switch screwed in from the driver's side, and the coolant temp sensor screwed in from the top between the intake runners.

I dunno what wire you're talking about...try tracing it out with an ohm meter when the car is off.

Are your taillight/parking lights always on as these two brown wires are hot?

My chiltons shows a tan/white wire feeding through the headlight switch to a brown wire and then to the tailight/parking lights. If both of those are hot, the tailight/parking lights should be on....unless the chilton's has the colors wrong and you're talking about different wires.

First thing I would suggest is pulling out the taillight/parking light fuse. If the lights go out, that means the headlight switch is toast and is staying on all the time. If the lights stay on then that means they're most likely getting fed through the brakelight switch, hazard switch, or the multifunction switch on the steering column.

I would then try unplugging the multifunction switch on the column. If the lights go out, that's the culprit...if not, repeat with the other two switches.

If unplugging all three switches doesn't turn the lights off then I would verify that your ground near the lights ohms out with the negative side of the battery.

If none of that points to the problem then you may have something funky going on with your wiring.

No prob. Just curious, which harness was it?