Read data from MCP9808

Try running require("Storage").eraseAll() just to ensure that nothing gets left in storage that shouldn't be there. That might help you a little.

Since RAM obviously works for you and you seem happy with that, try:

var mcp;

function onInit() {
  clearInterval();
  I2C1.setup({scl:D25,sda:D26, bitrate: 60000});
  mcp = require("MCP9808").connect(I2C1, 0b000);
  console.log("I2C Setup Finsih");
  ReadTemp();
};

function ReadTemp() {   
  setInterval (function() {
    digitalWrite(LED1,0);
    var temperature = mcp.getTemperature();
    var TimeStemp = new Date().toString();
    console.log(TimeStemp + "  :  " + "Temperature: " + temperature + " C");
    setTimeout(function(){
      digitalWrite(LED1,1);
    },5000);
  } , 10000);
}

onInit();