Doesn't sound like anything I've ever heard hypermiling could do, but it might just be messed up with age and sadness, cars get that way sometimes.
How much does a pcm reflash cost? Sounds like a waste to me, just buy one, at least for hondas they're like 30 bucks,
Welcome to ecomodder! Hopefully the jeep people on here will have a little bit more help for you.