There are a few problems with this schematic
1) You are using an ideal voltage source, You may want to add some inductance and resistance to simulate wires. Mains power is not infinite, and neither is the current from a transformer. Your transformer is going to have a lag on power that it can deliver, you should probably simulate this. Another thing to watch out for is transformer saturation. (unless your not getting power from AC mains)
2) As the other answers say, you have a huge capacitor, is throwing more capacitance at the problem going to be a good solution? If the current is too high, then you need to change the design, not the parameters of the design. At these current levels you should probably use a DC to DC instead of a vreg unless price is an important consideration. You are going to burn up lots of power. Its better to put smaller amounts of current at a higher voltage through the rectifier You can get cheap DC to DC regulators that are 780X drop in compatible that will handle 1 amp, you can parallel them if you need more current. If that doesn't work then go find a DC to DC IC. Have you considered a AC to DC power supply such as a "wall wart"? People make these things for less than 20$.