Kia sportage idle problems

My Kia Sportage 1998 keeps acting up on me.

The idle goes up and down. The car will shut off wighout any warning. I sounds like it is running out of gas or air. We have changed the air filter, the gas filter, the gas pump and nothing works. We run out of parts to change. Help! Does anybody know what is wrong with my car???

It may be a vacuum leak around the intake manifold, intake tube, or vacuum hoses.

Thank you for your for replying. We will look into that.

Does anybody have any other sugestion to this problem?