Milage improvement mods that really work?

[clr4theapch]

Sorry for the title, been reading this forum for a while.. I have the big engine 2004 Freestar SEL.. so far its been a very comfortable and reliable van.. howeve the has milage really does sssssuck... 17 to 18 hwy at normal 70 to 75 mph..

I was wondering if anyone has come up with good methods (short of shooting it) to get better economy...

Are there better plugs or a MSD ingnition sytems that might promote better fuel burns? I have a K&N airfilter installed..

I thought about removing seats to lower weight.. gone a diet myself I just seems with all the great V-6 engines out in the world, that something has to be available now, that would greatly help imporve milage..

Thanks for the Ideas, and help for everyone here..