So I recently encountered a problem with my ranger not running right past half throttle. It runs fine in park and revs like it should but when I put it in gear it boggs and stalls out. It isn’t throwing any codes what so ever but I was thinking it may be the down stream o2 sensor.

 

Welcome to the forum

Please include YEAR of Ranger and engine size in posts so we don't have to look up your profile each time, I know I thought mine would just come up as well, lol, or you can put it in your signature

So 2000 Ranger with 3.0l V6

Clean the MAF sensor, then clean it again
Its bogging "under load" which means computer's air/fuel mix is not correct

It could be a vacuum leak or failing fuel pump, or, or, or..........., but MAF sensors should be cleaned once a year, so try that first, not hard to do and its a common source of bogging symptom

 

I cleaned the air flow sensor and the problem has persisted. Any ideas where to go from there?

 

If you have a smart phone I would invest $25 in a Bluetooth OBD2 Reader, elm327 is fine, and can be under $15

I recently got a BlueDriver OBD2 reader, cost quite a bit more but can also read transmission codes

These work on ANY vehicle sold in North America since 1996, its the LAW, so not a Ford thing

With that you can look at LIVE data for all the sensors
This might show you if throttle sensor is dropping out or ECT sensor has a dead spot
Or if transmission sensor the 3,000 REV limiter to kick in

Otherwise its just guessing

Which I don't mind, and even a blind squirrel finds a nut now and then
So test fuel pressure, hold RPMs at 2,500 and pressure should be 55psi, and stable, if its dropping you have failing fuel pump

Change PCV Valve

After engine is warmed up and idling
Unplug IAC Valve
RPMs should drop to 500 or engine may even stall, either is GOOD, no vacuum leaks
If RPMs don't drop you have a vacuum leak