Adjust the tensioner. I did the same thing thinkin it could be this that or the pulley. Adjusted that tensioner tight as can be and it went away. Another cause would be the air compressor pump itself. Sometimes it ties up and doesn't move freely and the serptine belt will squeel around it. A tell tail sign of this is a bad smell after/during running. Another way to know if this is starting is if it only squeels for a little bit and then stops. This is about a $500 job. You either have a worn belt that needs replacing or your belt tension is insufficient and needs to be tightened.
Is the TCM working normally and throwing no codes?
My '96 Cherokee Sport does, so I bet a '98 does.
The grand Cherokee is a body style, sport is a trim package that is used on all jeep models(wrangler, Cherokee, grand Cherokee, patriot, ...)
The fuel pump is in the gas tank on a 1999 jeep Cherokee sport.
Yes, they are the same vehicle, the sport is just a option package.
1996-2000 Cherokee.
The switch is probably bad or you aren't turning the knob all the way off.
NoNo
Jeep Cherokee XJ 1984-1996 should interchange Jeep Cherokee XJ 1997-2001 should interchange
Sport, Country Classic, Limited, (and others) are the names of available option packages. You basic 1984-2001 Cherokee is pretty much the same as any other Cherokee.
No, the XJ Cherokee does not have the same heater box as a WJ Grand Cherokee.
It is one of the available trim packages.