PLZ HELP idles rough then dies

[BOWLING91]

i got 92 sport explorer and when i let it idle in park it will idle fine for a while then start running on a couple cylinders then it will eventually die. but when it is in drive it will idle fine forever. i have checked idle air, tp, mass air, it has a new coil pack, new ect. fuel pressure at idle slowly goes from 20 to 30 psi. it will also die if i flat foot it every once and awhile. what could be wrong? and when it was in the negatives one morning wouldnot even hit once, cranked good just would not hit. when i came back when it was warmer it took a couple tries then fired right up. HELP PLZ!!!!!!

 

[FIND]

Any trouble codes? You can remove and clean your IACV for a start.

 

[MrShorty]

fuel pressure at idle slowly goes from 20 to 30 psi.

Does it stay at 30 psi? Is the fuel pressure still 30 psi when the engine stumbles/stalls? What doe sthe fuel pressure do if you disconnect and plug the vacuum line to the FPR? With the vacuum line connected, the fuel pressure should come up to 40 psi when the key is turned on and drop to ~30 at idle. With the vacuum line disconnected, the fuel pressure should hold steady at about 40 psi under all conditions. It should never be 20 psi unless the system isn't holding pressure when the pump is off (which shouldn't be a big deal as long as the pressure comes up to 30+ and never drops below that while the engine's running). If you haven't already, I'd spend a little more time to make sure the fuel system is doing what it should be.

 

[BOWLING91]

i have not messed with the fpr yet. im going to when i get home from lima this weekend. and um yea but it sometimes does not get to 30 stays under it. i think pump is weak or has a bad connection at tank. gonna replace fpr for the first time and fuel pump again probably. if not fuel im gonna look at the cat it smells really rich when it runs. then goona look for a big vacuum leak somewhere. for the other person who said something about the IAT i have put two different ones on and both are pretty clean and it still does it. also has never thrown codes.

 

[Roadrunner777]

I had something like this on another vehicle, very specific at 32 degrees F, colder than that and no start. Changed the fuel filter and the problem went away. Old filter had some purple sludge in it.

 

[BOWLING91]

just changed fuel filter about two months ago.

 

[BOWLING91]

fuel pressure is really good and today was rainy outside (dont no if that has anything to do with it) and it ran normal. the only time it ran bad today was when i first started it then it ran fine. it has always had a little bit of a rough idle since i have owned it.