I have 99 suburban back brake is get extremely hot seems like back brake drums are holding more than front brakes discs has new brake lines hoses master cylinder and shoes on rear

 

Is the parking brake on? This has a parking brake brake shoe that could be locked up.

 

As @kevinkpk said, the park/emergency brake mechanism needs looked at plus all the rear shoes and hardware as well. The hold down pins could be broken, the return springs may be stretched and something lots of people overlook is the backing plates need inspected to be sure they are flat and smooth where the shoes move across. Can get grooves that keep the shoes from returning to a rest position when pedal is released. Check for proper shoe adjustment and proper park brake adjustment. Also, if has gotten that hot, the fluid needs to be flushed out. Make sure the rod that fits in back of the master cylinder is adjusted right, if it is adjustable. There also could be a problem with the proportioning valve. When you apply the brakes, the rear shoes rub first so that if the road is slick it drags the rear to keep from the rear coming around on you and then the front brakes apply to do most of the brake action. A bad proportioning valve can cause problems as well.

 

rear drum brakes.
Can you remove the brake drum? Do they spin with a slight drag?
They may need the adjuster backed off if they are adjusted too tight.

 

I have a sub 6.5TD, 1500, 1996,,,,

I sometime use 2 "flush" the rear break-drums with fresh water. Only use the water-hose, and do 2 good flush into the drum from the inside (you do put yourself under the rear of the car), let the water get int2 the drum, from top 2 bottom,,,, and perhaps it would be some help.... The meaning of this is 2 flush out the break-dust from the system (break-shoe and the drum), cause the dust will be collect into this and make some fuzz when break. Perhaps you will also notice the water become grey/dark when flush. You can also remove the 3 small hatches and push/squirt the water into them. When done, do not leave you car with the breake on for "a longer time", do not do that cause the brake can fasten (the water will quicly make rust inside the drum). Perhaps the best is 2 drive a short trip and use you break for some very short time so the water inside will be removed..... Until the water is out, you can perhaps experience the breaks rear "chop"/hang (do not know the US-word) Do this flush-procedure now an then.

Regards from Norway.....

 

Here is what my 99 did, and my 65 Malibu also. There are three(3) flexible lines on your 99. One each on the front wheels and one that connects to your rear axel. You did not say which ones were replaced, the steel ones or the rubber ones. The rubber ones over time swells up and when you apply the brakes the swelling does not allow the pressure to release, in other words the brake pressure you applied is maintained by the swollen line. If you have new rubber lines then maybe you have one of the other problems suggested above.