I have 2004, 5.4, 4x4. Efans, 3.5" af1 intake, magnaflow sido, and custom troyer tunes for 87 performance. First it would shut off when I came to a stop or coasting down a hill, never under throttle. I then bumped the idle rpms to 650, its pretty much stopped shutting itself off other than when I shift into park... it will very consistently shut off. Besides bumping the rpms up again... does this sound like a more serious problem?

 

I would suggest you call them and ask them if it is something that they are familiar with. I doubt if you will find the answer you seek here.

 

Did this happen right after one of your mods, or just randomly? Does it idle fine in D before and after the bump in RPMs?

 

yes it idels fine now and cruises fine but shuts off when i shift to park

 

Sounds like a tree hugger got under your trucks.

I wonder if your fuel pressure is getting low. Might change the fuel filter and see if that helps.

 

no codes being thrown, fuel filter is 5k old, how could i check fuel pressure

 

Did you try setting the tune back to stock...