[nemo]

A step back to go forward? Too slow of acceleration (as other have said) will use more fuel, try 2.2K to 2.3K in first and second. Again without instantaneous MPG read out your are just guessing, get some kind of gauge and keep a fuel log. I haven found putting it in neutral at lights to be much of a fuel saver, however no AC and shutting it off do.

On a heavy vehicle a key point is when you lift and coast length. Up your tire pressure if you haven't. What type of commute or driving do you do? If you do much city driving the lights and timing my not allow you to reach the speed limit between lights before you need to back out.

Let us know what works for you.

Good luck.