318 MAX fuel economy builds?

One other thing that happened to my van that had the millage up to 16 mpg. I was chasing a problem with the engine not running right, changed every part at least twice. It would buck jump under the slightest hill climb, regular hill no problem, maybe a 2% grade. Well by chance I changed the crank sensor, bam ran like a top but then after that came the 12 mpg. Still trying to figure how that sensor caused that difference because it’s only picking up a signal when to fire. Any ideas guys? Can’t find that dang sensor to retry.