The first two do little to help MPG, the K&N filter does nothing but pass dirt, the 4th is way past due maintenance on most every MB diesel. It looks like you got everything running closer to what it should be.

A better change to raise MPG would be to swap that 3.69 rear end for a 3.46 ratio. Advance the timing to 26-28*BTDC and get the cam back in time with the crank. Swap in the larger turbodiesel radiator and your electric fan will come on even less.