I have done quite a bit of reading about possible things involving the rough idle with my ranger. I have replaced the mass air sensor, replaced coil and PCV valve. I do not want to just keep replacing things does anyone have any suggestions. Thanks, Coop

 

is yours a flex fuel engine?

 

No it is not

 

Does it start normally? Does it Run normally?

 

Pull out all 6 spark plugs, and look at the tips of each, keep them in order, see if you can ID any that are different than the others, darker or light brownish color
Clean spark plugs, regap, and reinstall

Fuel injector tips get dirty, just normal build up, if you add a can of Seafoam to the gas tank it will clean the tips over about 1/2-3/4 of a tank, I do this once a year in my fuel injected vehicles.
A Dirty tip drips fuel instead of spraying, and at idle that will cause misfires, at higher RPMs air flow is much fast and dripped fuel gets mixed better

Test for vacuum leak, its easy
Warmed up engine
let it idle
Unplug the 2 wire connector on IAC Valve
Engine idle should drop to 500rpm or engine may even stall, either is GOOD it means no Vacuum Leak
If RPMs do not drop then there is a vacuum leak

 

It starts normally and idles fine. As soon as gas is applied shaking and surging

 

Which one? idles fine or idles rough?

 

I have replaced mass air sensor pcv valve and coil that fixed the rough idol. Now as soon as you press the gas runs really rough and surging