Chevrolet: 2001 Tahoe-low coolant/low fuel light, chevy silverado, chevy tahoe

Question
I have a 2001 Chevy Tahoe, I have had it since June 2004.  Periodically I would notice if I was not on a level surface the low coolant light would come on.  I have been ignoring it becaue I figured the sensor was just touchy.  In the last 6 months the low fuel light comes on and the gas guage goes crazy (goes up and down and will sometimes stay on the correct fuel level for a while, then goes down to empty again).  I have been told that I need a new fuel sensor but I won't replace it because it will cost over $700.  Now I am noticing that the low coolant light comes on and off when ever it feels like it, as well as the gas guage and light freaking out.  What would the low coolant light have to do with the fuel sensor?  I am thinking maybe that was not the right diagnosis?  By the way, my husband has a 2000 Chevy Silverado and it does the same exact thig.  Both our vehicles have a little over 70,000 miles.  Let me know if you think there might be an electical problem or something else I should have the mechanic check.
Thanks for any help/advice you can provide.

Answer
TAMI;
  Hi  well I wonder if you have a computer problem , or if you should just have it put on a computer to see what codes show up and they will tell you  what the trouble is.
As far as a fuel sensor it would have nothing to do with the coolent level  - so I wonder if there could be a obd error  on boad diagn.problem .and if a computer adj. might fix it for you. at times just a loose gas cap will cause the check engine light to come on - so it could be a lot of things. ok