What do i use to fix a hair line crack in my 1997 jeep grand cherokee

all the same day? check all fuses first. as always for electrical.
is only the fuel gauge and only the windows failing , all windows failing and at all locations.. sounds to me this is cumulative failures not all at once, right?
check the fuses. then again
the best fuse test is with a volt meter , key on, 12vdc on both sides, not 0volts.
send best is to check them for 0 ohms (not infinity ) pulled.

fuses that look bad are bad.
fuses that look good can in fact have hair line cracks a human can not see.
tell more, get more. I have full doc;s on jeeps.

sounds to me like you have vacuum leak or manifold leak. See if you can hear you intake sucking air my need to replace gasket or check vacum line loose or cracked

should replace or try some seals.rislone liquid stop leak[alum.]

98 grand cherokee limited 5.2L same problem found leak not from heater box but from drain mount on firewall under the glove box not behind it. drain line should be located behind right front tire in the frame. Turn your wheels hard left look inside fender well right side towards back side. hole in frame where drain line should come out.

there is a rpm magnet that bolt on top of your transmission i had a jeep that done the same thing and repleced that and havent had a problem sinceits located on the left top side of your tranny has one little bolt that holds it in and a wire coming off of it that should fix your problem.

I think this indicates that you have an exterior light out. Check the tail lights, brake lights and the three bulbs that are mounted at the top of the rear window.

test for vacum leak under hood on driver side firewall plastic line goes to rubber with check valve most of the time rubber line has hole in it

left rear of engine block,on transmission bell housing.best way from top under brake booster use a wrench,

Yes, you should replace it. This canister is to take the fumes from your gas tank into your engine. You need this to pass your state smog test.

There is a vacuum leak under the hood. If it's a 6 cylinder, look on the drivers side for a vacuum line that runs vertical with a 90 degree angle fitting to the manifold. That one usually comes off. If it is a V8 look on the battery side for a broken or corroded vacuum line.