To fix the stalling, there is a black plastic line that goes from the
driver's side of the engine down to the vac switch on the driver's side
of the transfer case. Find the line and plug it, that should get your
engine running correctly. If not, keep working on the vac lines.

To check out the vac operated axle disconnect, hook up the vac line to
the transfer case switch. With the engine running, CAREFULLY pull the
connector to the front axle off the vac motor. The green line should
have a slight vac with the transfer case in 2wd, the yellow line should
have vac in 4wd. If it doesn't switch back and forth, replace the vac
switch on the transfer case, $25 from the dealer. If no vac on either,
you have a bad vac line somewhere.

Your symptoms sound like a cracked vac line or trashed rubber connector
for the line to the switch or vac motor. Pretty common for that vintage
Jeep.

Jeremy wrote:
> I have a 1990 Jeep Wrangler who's vacuum lines have been disconnected.
> I need help sorting them out as to what goes where. I think I have most
> of them connected properly but my 4 wheel drive light is on, but when
> you ramp up the rpms it goes out. I just need some help getting the
> lines in their proper places so the Wrangler idles rather than
> stalling.
>
> Thanks for the help
> Jeremy
>