I am having a problem with my 1996 f150 ford pickup it has the 4.9 straight 6 in it .I have out on new plugs . plugs wires.distributer cap.new rotor button.funs great .F.till u kill it .it will start back several times in a row just great. Walk away for a while an will not start for nothing walk away again 10 or 15 min come back an it will start up .like I said runs great at idle. Runs great going down road .but when u stop it for a while it takes an act of Congress to get it started again. I need help

 

was it doing this before you put all the new parts on ?

check for codes. there can be codes waiting for you, even if the 'check engine light' is not on.

 

My guess would be gas is leaking down into the cylinders. Possibly from a bad fuel injector regulator.