1997 Jeep GC 4.0 starts, then Dies, MN Cold

[niero]

Cleaned TB

I cleaned the throttle body. Just the fact that I was able to remove a part such as the intake hose connected to the TB is pretty cool. I know that's a blatantly easy thing to do, but it's cool to know that I can actually do some of these minor things as long as I am slow and thorough.

Sprayed about 3/4 of a can of the NAPA CRC Throttle Body Cleaner. After about a half can the engine started sounding a little different so I figured better safe than sorry. I wasn't sure if you should use the whole thing.

Let it sit for 17 min. Started engine, revved numerous times into the 300 - 4000 rpm range. Took it out on the freeway and kept gunning it, getting rpms into the 4500+ range several times.
It seems to have helped a bit. But the issue is still there.

Is it safe to clean the TB again or is that hard on the engine?


Next things:
Cat conv - My cat converter has always rattle b/c there's some metal piece inside. But supposedly it's still good.

Vacuum leak - The shop has mentioned a couple times that there is a vacuum leak. What does that mean?

Thanks.

 

[niero]

After cleaning the throttle body, I checked the tranny fluid. It was definitely low. Have topped it off, and it seemed to help the issue, but it's still there.

I'm thinking it may be the cat converter, as there's always been a metal piece or two inside that rattles.

Is a cat converter difficult to replace?