I have a 2004 ford f150 hertaige. 4.2 v6. Manual 5 speed. It has a rough idle. After it is cranked it idles high then low. When down shifting it can shut off.
When hooked up to a computer one day it may show 4 codes then the next 8 codes. Every code refers to mixture to lean. I have replaced the MAF sensor twice, upper intake gasket, intake hose, both upper o2 sensors, PVC, Idle Air Control valve, TPS, Air filter, fuel filter, spark plugs and wires. After relacing some MAF sensor the showed that it wasn't working.

This doesn't include the new tires, brakes, rotars, wheel bearings, and alternator that I put on it. I have taken it to a mechanic they said that they do not know what is wrong with it. I have not replaced the iginiton coil or the egr valve. I am begining to think that the computer is gone out after 113000 miles. Any suggestions before i put a for sale sign on it.

 

What are the codes you get?
What is the fuel pressure?
Voltage feeds to the TPS and IAC and Mass Air need to be checked as it may be an electrical/harness issue and not a sensor.
A shop with a good scanner can see the operating data live to get some idea of what is happening.
Bottom line is better troubleshooting is needed beyond parts replacement.
Good luck.

 

Did you take it the dealer? I've found if I cant figure it out it needs to go to the dealer. Most mechanic's are no better at diagnostics then I am though so if I cant figure it out the dealer is the place. Most of your average jack of all cars shops dont have the resources to train tech's on every cars diagnostic routines. Ford dealers focus on Fords..