im having the same thing with my '99. replaced egr valve and sensor as cel is coding p0401 but didnt help. Havnt changed egr solenoid yet. Havnt cleaned throttle body yet either. Could plugs or coil pack b causing trouble. Replaced plugs at 100,000 miles. Now have 230,000. any ideas?

 

Try this:
http://www.eniva.com/Doc/Super21Directions.pdf

You're probably thinking: garbage! I used to think that as well so tried it myself to see what the real story is and it really does work. And yes, I am one of their distributors so may be totally biased lol, but try it and decide for yourself..

 

Your EGR passages in the throttle body are plugged. Remove the throttle body and clean it.

You are also overdue for another plug change.

 

ok cleaned throttle body and changed plugs. ran fine for bout 6 miles then started sputter at overdrive but not quite as bad. got the cel to go off so not having egr trouble anymore just need ideas on wat could still b causin the sputter at acceleration of overdrive. havnt changed plug wires yet. could it b fuel filter? anybody got anything?

 

Do you have cops or coil packs and wires?

 

have wires. HAvnt changed them yet. sputters bad wen take off but gets little better as drive. still tries to sputter at acceleration in overdrive but not as bad since changed plugs. could it b throttle body sensor since it sputters wen put in gear? maybe thinkin catalytic converter no sure.

 

probably wire or coils. Start with the wires. Motorcraft wire are best. You can get them at Rock Auto on the internet at a substantial discount. Same with the coils..The throttle body really dont have anything that will make the engine missfire. Maybe if you had a really big vacuum leak..

 

sounds like the same problem i had with my 98 ended up being a bad fuel injector. had it changed, and now runs good again

 

Was a solution found?

 

Yes. My neighbor is a mechanic and I had my truck in for service. 99 F-150 V6 and it had a gasket leak on the #1 cylinder which was going to require the head to come off. I had them replace the FUEL PRESSURE REGULATOR as I had tried all the other fixes like plugs, plug wires, etc which I believed was causing the occasional stumble. Mine always happened at highway speed.

My neighbor looked at me funny, but I insisted they replace it.

It was in such a pain in the *** to get to--you had to take the top of the engine apart just to get to the damned thing (a $40 part at O'Reilly).

Took care of the problem.