I have a 2003 Expedition 4.6L with 196,000 miles. The truck was running great, but I noticed that it would stall after driving a long distance. I never had any issues while driving, just after I came to a stop. The problem got worse the other day and I needed to keep my foot on the accelerator to stop it from stalling. I was able to get it home and checked the codes on it (p0506 and p0442). When the engine would stall, it would initially run at 800-900 rpm, but then drop to 200-300 and shortly thereafter stall out. I replaced the fuel filter and added fuel system cleaner which did not really help. Since replacing the filter, the stalling has gotten worse and the truck will now immediately stall after starting unless I continue to give it gas in which case it will run and sounds smooth. With the evap leak detected I took down the charcoal canister and solenoid (replaced the solenoid) and inspected the lines for leak which I could not find any. I also inspected the purge valve in which all lines look intact. I inspected the vacuum lines in the engine compartment and again these all seemed fine, including the elbows. I unplugged the PCV valve and I do have good suction. I took off the IAC and cleaned it, no change. The IAC is getting power and the there are about 9 ohms of resistance across it (which i read was a good test as to whether the solenoid was bad). I'm getting power to the MAF and it looks very clean. I have pressure in the fuel lines. I've gone through this forum and have tried nearly everything I could find that could possibly be causing this. I'm running out of options and would appreciate any help. Thanks.

 

The stalling is probably caused by a faulty IAC valve. Replace it.

 

Thanks, that's all it was

 

any other ideas. I have the same issue and replacing the IAC did not fix my issue.

 

A possible bad TPS, also if you're getting the P0442 code then make sure your gas cap is on correctly.

 

Try starting your own thread and actually list all your pertinent details. My recommendation to the other poster was based on the totality of the symptoms he described.

 

thank you will look into TPS. no codes are being sent out