There is a You Tubedeo named: "Zetec Engine Rough Idle - Issue solved"
In a nutshell, the person thought it was his MAF, turned out to be a crack in his air tube under the throttle body (vacuum leak).
2012 Toyota Sienna LE 2.7L 6AT (w/Convience Package + Preferred Package)
2000 Ford Focus ZX3 5MT (I want my MPG!)
1994 Toyota Supra 5MT (SZ-R Project Status: Retired, 2012 Speed Ventures Time Trial CC9 Champion)