I have had gassers too. The 4.6 Triton I had was LOUSY on MPG. Not towing the best I could do was maybe 14. Towing? A total joke. You could watch the fuel gauge drop when driving.Good motor but bad fuel milage. Lots of guys here are running deisels. If you do a lot of stop and start with no extended running to "clean" the motor out then I would say stay with the gasser. I put on maybe 300 miles a week over 6 days. Two of those days I run 25 miles to and from accounts in another city that let me run the truck at 65-70 mph. Just enough to blow the cobwebs out. Over the course of a year the savings in fuel costs driving the deisel vs. the gasser make it worth it.(MPG wise) At least for me.