Ryan, if you decide to get a PCV valve, be sure to get one directly from a Dodge parts department, they have very specific tolerances.
If you haven't changed your plugs yet, that may be another option for you. You can get the 16 NGK 5306's you need for about $40.00 and plan on about 3 hours to do it yourself.
If there is any possible way to get rid of the throttle body spacer, I would do it. I have never read or heard of anyone gaining anything from a throttle body spacer.
It wouldn't hurt to reset your PCM by pulling the appropriate fuse. There's a post made here somewhere about the correct fuse/procedure for your '05.
Adding a bottle of fuel injector cleaner to your next tank wouldn't hurt either.
It also wouldn't hurt to try using a different gas either, a different brand that is.
The very best mileage I've ever gotten from my '03 was 16.4 mpg - all highway, right after I'd cleaned my TB, changed my PCV valve and spark plugs. My truck averages between 8 and 9 mpg winter around town and 11 to 12 during the summer months. Fortunately for me, I'm lucky if I put 2,000 miles a year on my truck.
You've probably done lots and lots of reading in the forums already, but keep looking and you'll find many other hints and tips and tricks that others have tried with some successes.