Does this sound like a vacuum leak?

Question

I have been having issues with my car for forever it seems like. I got the tranny replaced in March and it has been going downhill ever since then.

Like I said, I got the tranny replaced, replaced both cv axles, all brand new tires and aligned, just got a tuneup on Saturday, the oil is fine.

Ever since I got my tranny replaced, it seemed to be running high RPM's. Higher than before the old tranny went out. It's at like 3500 going 70MPH.

I bought the car and it got 260 MPG [11gallon tank], it gradually dropped to 150 MPG [which has imprved since the tune up, but still not right]. I took it back to the mechanic multiple times thinking it was the transmission. They keep telling me it's fine. Well, last night someone had suggested a vacuum leak. Here are the symptoms:

High RPM's

Loss of power

Drop in fuel economy

A/C acts up occasionally

Smells like burnt rubber under my hood

My car says it should idle at 800 give or take 100, and it idles fine.

Im thinking there is a vacuum hose touching something hot and literally burning [hence the burnt rubber smell], and causing there to be a leak.

How can I find this out?

The car is a 2000 Hyundai Tiburon.

Answer 1

soundls like the catalytic converter thats what  my 2002 grand am was doing and i had a back pressure test done then they told me it was my catalytic converter i put a new one on and it ran better then when i bought the car.