What is the problem? on 2003 Ford F-150 Lightning

When i start my truck it runs fine for about ten second. then the rpms ease down and it begins to sputter(in park and neutral)acting like it wants to die but in drive and reverse it runs great Whats causing this?

Asked by for the 2003 Ford F-150 Lightning
is your ck eng light on? if so have codes read at auto zone for free and post so we can advise
sounds like your pcv hose is leaking vac and possibly your dpfe valve is bad or hoses going to it. you can find the air leak with a smoke test.if its a 4.2l you may have an intake leak which is common on that motor
I've checked all the hoses and replaced the egr valve since it was a little clogged but my fuel pressure gauge started acting up not to long ago and now doesn't work could I possibly have a fuel injector problem?
ck what i adv on 1st