spark wires burning through, located near exhaust manifold

I have a 2000 pontiac bonneville SSEI with a 3800 supercharged engine, with 130000 miles. Catalytic converter failed replaced it. A few days later the brake booster failed replaced it, but now brake pedal is a little soft when the car first started, brakes have been bleed, but no help. I have given up on that for now. The real problem is that I have had to replace the spark plug wires, after the ones located near the exhaust manifold closet to the catalytic converter burned up because of the heat of the exhaust system. Had new spark plug wires installed and now they are burning through. I have also noticed a small oil leak in the garage and the coolant reservoir loses coolant over a period of time, but never goes completely out. I have replaced the spark plugs, spark plug wires, catalytic converter, egr valve, brake booster, and O2 sensor in the last to weeks. What could be causing my exhaust system to overheat and my spark plug wires to burn through.

Thanks,
Please help me