poor MPG after tune up

You need to check your plugs to see what they look like to give you an indication. Sounds like somebody is synphening off some gas.

Should look as follows

Condition.......................Appearance........ ......................Outcome

Normal...............White (no color change) with light gray ring......Correct
Overheating........Extreme white with aluminum specs.................Lean
Wet..................Wet or sooty............................................. .Rich

Do you have any way of scanning your car? I'd still try and clean the MAF and see what happens since commanded fueling is partially based off the MAF sensor.