Truck is a 2011 Ranger XL 2.3 duratec

For about two months now I've been experiencing a definite lack of power when accelerating. However, on a cold morning when I start the truck it is the worst. It will start up fine and then I'll go to give it gas after pulling out of the drive way and it will just completely bog out. After a 30 seconds or so of giving it a tad bit of gas it will allow me to get my revs up and then everythings fine (aside from the lack of power of course). Truck pulls a rich code intermittently (P0172). The code will pop up after about a week or less of driving, just randomly. I am always clearing the code after replacing parts to see if it will pop back up again. Took the pressure at the fuel rail and it was like 85 psi, so it appeared to have a pad regulator or pump. I went ahead and replaced the whole fuel pump as the regulator is apparently part of the fuel pump assembly on these ones. After doing so, my pressure at the fuel rail was vastly improved from about 85 psi to 58-60 psi. Unfortunately, the lack of power issue still persists and after spraying down with carb cleaner I couldnt find any obvious vacuum leaks. I've replaced so many parts, as I am not a mechanic.. I'd love to take it in and have someone look at it but I love learning this stuff and I am determined to figure this out and learn even more then I already have... #1 being learn how to troubleshoot and stop replacing parts lol

So far, I've changed out:

Throttle Position Sensor
Thermostat
Engine Coolant Temp Sensor
All spark plugs
All spark plug wires
All fuel Injectors
All 02 sensors
Intake manifold gasket (just to be sure)
Valve cover gasket (found a little oil on two of the plugs so I did it just to be sure)
Fuel Pump
Cleaned MAF

What should I do next? The brake booster appears to be fine and as I mentioned before, I havent found any obvious vacuum leaks. Does this sound like an EGR problem? It would make sense in my head, but I figured I'd ask the pros before digging into this, as it sits right on the firewall pretty much and is going to be a nightmare to replace.

 

Put a longer vacuum hose on the EGR valve and start the engine
Suck on the hose to open EGR valve and engine should start to stumble, if so valve is working and its CLOSED when it should be, assuming idle is OK

Leave vehicle's EGR hose disconnected from EGR valve and plug that hose end with a screw or ??, it only has vacuum when computer activates EGR valve but does have vacuum when computer activates EGR valve, lol, so would be a vacuum leak at that time
Go for a drive to see if the stumbling is gone.

You will get a code set because EGR valve is unhooked.

Yes that 85psi fuel pressure would set Rich code


To test for vacuum leak, warm up the engine to operating temp, let it idle
Unplug the IAC Valve's 2 wire connector, it will then close all the way
RPMs should drop to about 500 or engine may even stall, either is GOOD, it means no vacuum leaks
If idle doesn't drop then there is a leak or IAC Valve is stuck

On cold start engine RPMs should be high, thats the computer Choking the engine because its cold, and that requires working IAC Valve and ECT(coolant temp) sensor
As engine warms up computer will start to close IAC Valve to lower the idle RPMs, is idle should drop down slowly during first 5 minute after cold start

 

Thanks so much for such a detailed response! I learned a ton from what you just replied. That information is going to help me tremendously! I am definitely going to be trying all of the above to verify.

Quick question for myself and anyone anyone in the future, as their arent many threads that I have found on post-2003 egr systems.. Being that the egr valve on these things are tucked between the firewall and the cylinder head with almost no access, how can you tell which vacuum line will be the correct one for the egr?

Thank you again!