I have a 1999 ranger xlt 4.0 5speed 201xxx miles. I bought it about a month ago and every once in awhile when you started it would bog down and act like it was gonna stall till you hit the gas then It was fine so last night decided to tune it up so I changed fuel filter plugs and wires and the oil. went to start it for the first time this morning and it will start then immediately stall if you start it and hold the gas pedal it will idle really rough then all the sudden take off and run fine but when left off gas it will bog down and then stall.. so got to playing around and took the mass air flow tube off the throttle body started it and now it will stay running but super rough idle and ****ty running and only at about 2-300 rpm but eventually will stall and every time you put maf tube back on immediately shuts off i have cleaned mass air flow sensor I checked fuel pressure and coil and wires and firing order when I put it on the computer it says mass airflow low input just trying to figure out what could be wrong any help would be hugely appreciated

 

are you absolutely sure the plug wires are correct? if you switch a wire or two the engine will run but will run rough. also make sure there isnt something physically blocking the air filter. this time of year chipmunks love to make nests in mine.

 

Possibly a sticking or bad Idle Air Control valve.