I need the vacuum hose diagram for a 1988 ford crown vic 5.0 ltd

No, it would be the charging system. As the engine RPM increases, so does the output of the alternator. If the battery is weak, or maybe the alternator is overcharging. This is where I would start to look. But the fan motor is electric, has nothing to do with vacuum.

HERE'S A LINK TO YOUR WIRING DIAGRAM FOR YOUR RADIO. http://stereowiringdiagram.info/1988-ford-crown-victoria

I have a 1984 Crown Victoria and I'm trying to find the OBD plug in, If you know if it has a plug let me know where it is, thanks!

1991 Ford Crown Victoria
5.0 liter V-8 VIN "F"

Under hood, driver side, upper firewall, mounted above power brake booster. You can buy the diagram for the engine at several places online.

Try this site
http://www.eautorepair.net/

i am trying to install an aftermarket temperature guage with capillary tube into my 1988 crown victoria ltd 5.0 efi. where does the capillary tube mount?

make sure you have vacume too the control diapram

from a 5.8 liter truck pretty sure it is the same. hope it helps!