I have a 2002 F 250 with the 7.3 in it. It is all stock nothing has been done to it. In the mornings only the truck will just fall flat on its face . no throttle response. It runs rough at an idle. It does not die . After about 10 seconds I can give it throttle and it seems to clear itself out

SOURCE: truck starts, dies. truck runs good some days,bad the next

I had the same problem with My 1990 F150 300 6cylinder 4x4.....I cahnged all the same things you did, finally I sprayed a can of Gumout through the throttle body and it worked and ran great. Now I add fuel injector cleaner to the gas and a regular clean with the gumout and the problem has'nt come back. Good Luck to you and hope it works!

Marvin

• 85242 Answers
• Posted on Nov 04, 2008

SOURCE: idles rough

Check for engine vacuum leaks, most likely around the upper intake manifold arear, look for vacuum hoses that have come off or a missing vacuum port block off cap at the rear of the engine drivers side, large cap.

SOURCE: truck runs rough

Sounds like one of your chambers isn't firing. Run your car for a few minutes, shut it off then pull your plugs one at a time and see if one of them is wet. Might just need a new plug.

SOURCE: Idles rough when cold

the throttle body is icing. there are engine coolent lines running to the intake plentum. flush youre cooling system and see if that fixes it

SOURCE: 1988 ford f150 running rough

Might want to change o2 sensor's, If they are not sending the right single its tell the computer to dump fuel. 1988 was using a fuel density system.
(1989 came out with Mass air flow system)
Check this
I think it might have a TFI module that's not working right. Located under distributor. Its gray and about 4" long and if equip, you need a 4 or 5.5 mm tool to unbolt it. This was a common thing back in the 80's. Its been so long I can't remember if the 4.9 straight 6 had it or not.
T- Thick
F- Film
I- Ignition module