Exhaust leak?

[R2D21805]

Howdy Folks!
Can't find this issue in the forums. My wife has a 98 Sable and the heater and A/C work fine, but if I'm in stop and go traffic or slow traffic, I get exhaust fumes in the car, only when I have the A/C or heat on. I get heat, I get A/C but it all comes when the dangerous headache inducing fumes from under the hood. You can smell the fumes standing in front of the car right after you start it. Being that she's pregnant with our first child, I only let her drive it on nice days when NO air of any sort is required from the cars system. Just crack the windows if needed. Otherwise she has to drive my Jeep, and I get in unpleasant Sable for the day.

Common sense says it's an exhaust leak around the exhaust manifold/header pipes area being sucked through the air system. Am I correct? I really just need to sell this POS, and get something completely different. I have a 2000 Jeep Cherokee Sport I've owned for 6 1/2 years, not a single problem and I'm at 180K+ miles so far. Maybe I should get a 2nd one?

[65comet]

The environmental controls in the Off position, Defrost Only and Max. Air conditioning will close the flapper door that allows outside air to come in through the outside vent at the lower passenger side of the windshield. All other position let in outside air. The exhaust on this car has a flex pipe connecting the rear half of the system to the front. 10 years is about the max life on that flex pipe, so it is time to get into an exhaust shop and price a replacement. Because it is a weave of metal to give it the flexibility, visual inspection may not readily show that it is bad.