96 cherokee sport 4.0L
Current symptoms: (1)sounds like air escaping from my brake booster when braking, on the pedal side of things. (2)brake pedal pressure also seems to have a dramatic effect on engine idle (when applying a decent amount of pressure and then releasing causes the engine to bog down, almost stalling on a few occasions) I'm assuming this is because of the boosters affect on the vacuum. (3)Rear brakes lock up WAY WAY too easily.

What led up to this: my brakes had always been in rough condition. one evening on my home from work my power brake booster fails, I slowly make my way to a shop. After a long process they replaced all the rear hardware,shoes,cylinders, front pads/rotors, brake booster, and master cylinder

So I'm wondering if it makes sense to think that I probably got a junk brake booster(causing the whooshing sound in my pedal and idle/vacuum issue) and that they either did a bad job bleeding my brakes or my proportioning valve is failing (causing more power to the rear brakes)?

Any ideas are appreciated thanks in advance PS: asking for the shop to take a second look isn't an option.

1. Brake boosters do make 'wooshing' sounds normally.
2. Fixing one thing can often reveal other problems that you had to begin with. You probably have other vacuum leaks, and now that you have possibly sealed one leak with new new booster the other leaks are leaking more than they were before.
3. If your brakes were not bled well you would not be able to put enough pressure on the brakes for them to lock up in the back.

Since your brakes were admittedly 'always been in rough shape', the rest of the engine bay is probably also 'in rough shape'.

Time to bust out the tools and get your eyes and hands on your Jeep to smooth out that roughness.

For the rear brakes, the self-adjusting mechanism might not have fully adjusted itself yet. Try driving in reverse and braking stiffly a few times.

I don't think that is the real issue, but it is a possibility. Drum brakes pretty much suck.

Your brakes might just be working properly, but it has been so long that they have that the difference is shocking to you. Don't let your brakes get in such poor condition again! It is your life, your friends and family with you, and others on the road...their lives depend on your brakes.

??

I don't know if the '96 drum brakes have the same adjusting mechanism as the Renixs, but they are 'self-adjusting' and that mechanism actuates while braking in reverse. There is also the slot that you can reach a screwdriver in and adjust them manually. The self-adjusting part compensates for shoe wear.

This ^^^ makes no sense. Could you please explain this in detail??
I thought the reason for going to a certified mechanic/shop was to pay for 100% satisfaction.

^^What he said^^

It was a shop I went to out of desperation. I needed the job done fast and close to my house because it's my only form of transportation and the north east hasn't had prime conditions for working in your drive way. It took multiple days to get it done and multiple altercations.
The first time I picked it up they had replaced everything except the power booster and mc, leaving me with new brakes but still in the same condition as when I dropped it off, I had asked them to completely fix the issue when I had originally dropped it off.
After going and getting myself a new mc and booster planning on doing it myself I noticed one of my speed sensors hanging down. I return to the shop to share my dissatisfaction, the mechanic who worked on it insisted that he would put in the mc and booster for free, saying to drop it off to get done the next day, well that kid didn't show up the next day, eventually they took care of it.
I don't trust them to touch my car again, could have saved myself time and money if I could have just done it in my drive way.

I wouldn't be surprised if I did just get use to having junk brakes but when I say they lock up too easily Im talking 20% brake pressure.

My 96 does have them. I believe any drum brake axle will have these adjusting slots and can be tightened by reversing vehicle and braking, or a screwdriver to turn the adjustment barrel.

AndrewK, I am no brake guru but could an improper proportioning valve have been installed? One designed for disk brakes, which would cause drums to lock up easily.
Are the front brakes working at all?

I honestly haven't really been able to tell if they're working, I was going to troubleshoot a couple things this weekend. The proportioning valve has never been replaced as far as I can tell.

Drum brakes use more fluid than a disc brake, so it'd be the opposite effect AFAIK.

Correct, I had it backwards. Thank you

Going to start with checking to make sure they adjusted the drums right and go from there.

Calipers use more fluid than wheel cylinders. That is why the reservoir in the master is larger for the front brakes than the rear. But as for the original question, why aren't you taking it back to the shop that did the work?

After a few altercations with the shop I no longer trust them to touch my jeep, I explained in further detail a few replies back.