1990 Nissan SE 6 cyl nothing in the cab works including the blower motor or gauges unless you rev it up after you crank it and wont stay working after you start driving it

SOURCE: 1990 olds 98 blower motor

I would start at the fuse. Does the blower motor turn off when the fuse is pulled? A relay is usually used in this circuit and can sometimes "stick" allowing the blower motor to receive constant power. A quick check to see if it is a wiring problem, switch or the relay its self would be to find the blower fan relay and see if there is another one of the value you can swap with it. If the problem goes away, chances are it is the relay but I always like to take a volt/ amp reading to double check my work. 
Dan

SOURCE: wont start without starting fluid

Could it be a plug up injector , have sewiing needle , stick it in the sprayer part of the injector on the carberator part

SOURCE: 1986 king cab

I've had similiar issues with a different vehicle. I had to purchase new plugs, rotor, and distributor/spark plug wires. I was running on three cylinders verses four. I did not notice until I was going up hills, where it required more power. If you have a tachometer, keep an eye on it. If it is running slower than it should that could be an indication that there is a problem with the wiring. (probably should be doing about 2500 rpm)

I had a Hyundai that did just the opposite. It would peg the tach to 3,000 rpm well before it was time to shift. Ended up being an ignition coil went bad, which takes the place of the distributer. I replaced the ignition coil and now the engine doesn't have to run as high.

SOURCE: headlights wont come on and bright lights won't stay on hold bright light switch and blower works

I had the same problem. The solution is simple; the ignition switch needs to be replaced. This is an easy do-it-yourself project. Here are instructions:
http://forums.vwvortex.com/zerothread?id=2532481
Check for a switch on ebay, they are about $15. After 10 years they wear out.

SOURCE: HEATER BLOWER MOTOR ONLY WORKS ON HIGH SPEED

THERE'S A SENSOR UNDER THE PASSENGER SIDE OF THE CAR UNDER THE GLOVE COMPARTMENT YOU HAVE TO LOOK WAY UNDER JUST LAY DOWN ON TOP OF THE MATT IN FRONT OF THE PASS SEAT IT HAS 2 SCREWS ON IT UNPLUG IT THEN UNSCREW IT TAKE IT TO THE DEALER IT COST ME ABOUT 30 TO 50 DOLLARS BUT THAT WAS THE PROBLEM I HAD. GOOD LUCK