My tachometer is not working on my 1991 chevy caprice

SOURCE: SHOW ME A ROUTING OF A SERPENTINE BELT FOR A 1991 CHEVY CAPRICE

try autozone.com to see if they have your car listed for diagrams pictures and step by step instructions if your car is not listed then try your local library they have all the car manuals and even copy them for you

SOURCE: my 1991 chevy caprice is having problems accelerat...

Though too much fuel can do that, it virtually always is not enough fuel at the transition to the more-open throttle setting.

You can also get his from
a vacuum leak
the float level being too low.
the main jets being partially blocked.
a defective accelerator pump (ruptured diaphragm, bad lip seal, etc)
a disconnected accelerator pump (though that is usually worse than you describe)
an accelerator pump not set to deliver enough fuel.

When you move to a higher power, the required increase in fuel flow takes a half second or so to get established, because fuel has mass; it cannot just suddenly flow faster. The accelerator pump is there to squirt fuel into the airstream as if from a squirt gun to cover the brief lag in flow response. (That's all it does. Increasing the flow of that pump past optimal does not increase power, it reduces it, making the response just a little more sluggish.)

SOURCE: 1991 chevy caprice taillights and dash lights dont

Your headlight switch is faulty, change it out. seen it happen where head lights would work only until switch was replaced