2004 Ram QC 4.7l spark plug suggestions

I tuned up truck last year with same plugs that were in truck. Seems that I was getting about 14-15 mpg in city and know down to 13mpg. Are there any better plugs that I could install that would get me back to the 14-15mpg in city driving? Engine idles perfect no missing has plenty of pep. Any other suggestions?

thanks

No Bosch plugs and Chrysler products run like crap with Bosch plugs

I ran the Autolite XP's in my 2000 Grand Cherokee w/ 4.7L, it ran great. I gained a few miles per gallon and it woke the motor right up.