2001 Ford Escape 3.0L v6 4x4. April 2011, misfiring cylinder #5, Ford replaced plug, coil pk and DPFE, ran great for 8 months, #4 cylinder started misfiring, lost power. Same thing that happened back in April, changed all plugs, DPFE, ERG valve, IAC. Idles great but can't rev over 2500 rpms. Sounds like it is flooding out was told it is starving for air or bad vacumm. The brakes are affected as well. Checked for bad vacumm hoses, found none. Each part that I replaced made it run a little beter but problem isn't solved. What could it be?