fuel gauge problem on 89 sentra

yep....problem.... :wtf: .....anyways.....here's a situation.....i'm drivin down the road.....fuel gauge reads 1/2........then at a stop or while drivin a minute later....it'll drop in between 1/4 nd 1/2.......then a minute later it'll come back to 1/2.....nd it'll keep on doin that.....anyways...i guess the float in the gas tank is gunked up (i wouldn't kno how or why?)......or someting related to it.....anyways...oh yea.....nd when i start up the car......i may have what i THINK is 3/4 of the tank full.....but the needle on the gauge cluster takes like 2 minutes to stop rising.....too slow i think....anyways....any suggestions?.....