Still rough idle 2.7l

So about 3 weeks ago my truck started running rough at idle and between 1500 and 1700 RPM while driving. So far I have replaced the following items. Spark plugs, coil packs, perch valve, intake manifold gasket, fuel injectors, cleans the throttle body, checked all evap lines for leagues, checked motor mounts, checked exhaust. Everything checks out and the truck does not have any codes. I can't figure it out but it seems to be slowly getting worse and I can definitely hear it when it is idling and definitely feel it when it is in gear. Any ideas?

 

What do your fuel trim number look like and does it start idling rough immediately off a cold start or does it get worse the longer it runs?

 

MAF ( Mass Air Flow Sensor ). Did you clean it?

If you have the 6 cylinder you could bypass the fuel resistor in front of the battery that controls the fuel pump speed fast of slow. Unplug the two wire connector and jump across them leaving the jumper in place.

If it gets better then the problem is more likely the resistor.

Check the fuel pressure by teeing into the fuel supply line going to the fuel rail.

Tank >> Filter >> Pump >> Fuel delivery tubing >> Fuel Rail >> Fuel Rail Regulator ( Set to ~ 40 - 41.7 PSI) >> Return to tank.

If you tee into the delivery tubing the regulator still works and reads the regulated pressure ~ 40 - 41.7 PSI.

If you dead head a gauge at the delivery tube it reads full pump pressure ~ 60 PSI.

While idling:
Standard: (40.8 to 41.7 psi)
• If the pressure is too high, replace the fuel pressure regulator.
• If the pressure is too low, check the connection between the fuel hose and fuel pump.

Stop the engine.
Check that the fuel pressure does not change for 5 minutes.
Standard: (21 psi)If the pressure is not as specified, check the fuel pump, pressure regulator and/or injector.

 

I've done everything to include cleaning the mass air flow meter. I just recently considered the possibility that it could be the PCV. I put some seafoam in the oil and have driven it about 20 mi and it seems to be smoothing out quite significantly. I've got a new PCV coming next week. I will post an update when I install the new one but it does seem to be running better.

 

But are you diagnosing these things or carpet bombing it with parts? It sounds harsh so I apologize but this sounds very costly already.

Unless the fuel was heavily diluted from short trip in the winter I don't see how the seafoam is helping? Especially since seafoam is also flammable to that disproves my speculation as if that were true it would get worse until you changed the oil.

To diag if it's the pcv valve just remove it, plug it then start the engine to see if it smooths out.

 

The truck has 160,000 mi. I bought it used so I do not know if they ever did a tune up. I only spent about $150 on parts and installed them all myself within an hour so I don't see how doing that was necessarily a bad thing. The spark plugs looked very worn and the fuel injectors were original. I do not understand what the point of stating that seafoam is flammable is. Per the companies guidance I am going to swap out the PCV on Wednesday when it arrives and change the oil once I hit 300 miles with the seafoam in it. Again, after doing all of these things nothing changed until I added the seafoam and drove it 25 mi. It seems to be getting better every time I drive it. This leads me to believe that the ventilation valve on the back of a valve cover was most likely clogged and is slowly unclogging due to the seafoam.