Re: MPG decreasing
Not sure how much I actually believe him but I just did some MAJOR surgery on a wrangler at work for oil consumption (cylinder heads due to worn valve guides) and piston rings (one new piston due to skirt wear)... The customer came back in like 2 weeks later with a failing front u-joint saying his mpgs went up like 3 whole miles per gallon since the repair (he had done about 1600 miles in that time), so he was pretty happy with me. Not that this 3.8l has ANYTHING to do with your dilemma but none the less, I just thought it was pretty interesting.
2005 Jeep Grand Cherokee - Gone but not forgotten!