Can I ,a very handy person, change the idle air bypass valve?
If so, some detail on 2004 Mercury Grand Marquis

The check engine light revealed it has to be replaced

Asked by for the 2004 Mercury Grand Marquis
Yes, it is really just 2 -> 8mm bolts and a gasket. Disconnect your battery negative terminal for 5 minutes to let the memory erase, then when you start your car, let it idle for awhile. It will idle faster than normal, then it will gently come down to a normal speed. Then drive your car, it will take a few miles for the computer to adapt to the new idle valve.
Thank you,did as you said & can't wait fot the better MPG!