Braking System on 1994 GMC Suburban 1500

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Ok, well we had hard brakes at one point, then a slight shudder, to a left front brake smoking! Stopped, then found the Fliud in Master Cylinder, slightly gooy..We then Flushed the system, 3-4 times. Have back brakes, but front is soft. Then, bought the hand vaccum pump, to shoot air out, still nothing! HELP! Is it the Vaccum Booster, or Master Cylinder?
(1) Answer
It sounds like someone may have put the wrong fluid in the master cylinder of your 1994 GMC Suburban 1500. If that is the case it may be necessary to replace all the rubber components in the system. That would include the master cylinder, all brake hoses, front brake calipers, rear wheel cylinders (calipers if disk brakes), and possibly the ABS valve assembly. It may be a good idea to have someone qualified in brake repairs try and confirm the extend of the fluid contamination if the is indeed your problem.