Burning smell and mushy brakes. Related?

99 4.0L AW4 NP242

This afternoon i fired up the Jeep to leave school, smelled a little bit of a burning smell, thought it was my buddies POS Pontiac, didn't think a whole lot of it. Well as i'm crawling through the demolition derby to leave the lot, the brakes feel really mushy. It's like they start to work, then the pedal will drop down and they slam on and squeel really bad, but the squeeling is normal. Then as i'm sitting i smell that burning smell again, and this time my buddy is already out of the lot, so it must be my Jeep. Seemed to run ok, temp did go past 210, wasn't sputtering or anything. My commute to school is 2 miles one way, but I do let her warm up completely before shutting her back off again. Could my cat be clogged up?

The fact that the brakes felt really mushy and the burning smell started at the same time has me wondering though. It's not like i was power braking or anything, just crawling at about 5mph at best, and it had been sitting for about 7.5 hours since this morning.

Any ideas/suggestions are appreciated. Thanks in advance.

Check your brake fuid resivoir, if it´s noticeably low, it probably means you have a leak someplace. Most often in the rear brake drums at the wheel brake cylinder. The brake fluid seeps onto the brake shoes and will make them swell, drag, heat and lock up on occasion. Though a 99 does seem a little new to have a bad wheel cylinder, it´s worth a look see. Low fluid in the resivoir is a sure tip off, something is leaking.

I checked that, and it's all good. Still smelled it today, but not nearly as bad.

Mushy brakes usually means air, the only way air is gonna get in there, is if the system is leaking, somebody let it in when changeing/servicing the brakes or the resivoir is low. You can tell if it´s air, if after you´ve pumped the brakes a few times, the pedal gets firmer. ABS systems are a whole different can of worms, usually when a valve is leaking down someplace the pump will run alot.
Check the wires for the rear O2 sensor, I´ve seen a bunch that were burnt. While your down there take a look at underside of the floor boards for signs of heat and for junk (leaves, branches or what not) stuck on top of the cat.
Had one old XJ (87) that had a mushy pedal, it was a leak in the vacuum booster. If you listened you could hear it suck vacuum.
A too hot cat or a rich running motor has a smell all it´s own, don´t know exactly how to describe it, but it always reminded me of a metalic smell. Kind of a unique odor, I just call burnt cat.

wow, thanks alot for the help. Spring break begins tomorrow, so i've got a whole week and a half of day time to mess with this thing. Will crawl around tomorrow.

Thanks again for the help!

well i crawled under there today, and couldn't find any debris on top of the cat. Also traced the brake lines and cables as far as I could, and found no obvious gashes or slices in them. Brakes seemed better today, and i didn't smell the burning this morning. Only thing I can calk the burning up to is cause of my short distance driving in the mornings (2 miles to school, and 2 back). But I work 6-7 days a week, and it's 10 miles to work, so there shouldn't be any stuff clogging up the cat.