f-150 stumbles at part throttle
 

95 F-150 4.9 5spd 2wd.

Truck starts and idles fine.

Sometimes during part throttle acceleration the truck stumbles, like it's running out of gas or losing spark. If you back off the throttle it will idle fine, if you give it more gas it will pull out of it.

Seems to happen more when it's cold.

Gas is good fuel filter is new.

Any ideas?

interested in this one....my 95 with the 4.9 does the same thing.....

Mine too. Dad called it a "miss". I thought when a truck misses it's random.

Mine has this problem and it falls on it's face a lot. Today it started to do the same thing but pulled thru the bog and BOLTED. Threw me back in my seat.

I don't know what it is.

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I would post this one and see what the electronic whiz's think.It could be something like a bad throttle position sensor.They will tell you to pull the codes and that is probably what you should do,then they can tell you what they are.Good luck with it,electronics are my weak point,guess I'm just too old.I was running HP points in my '68 GTO,you weren't even born yet.lol:)

important

what kind spark plugs's wires, dist cap, rotor and coil?

Are they motorcraft? I try auto zone it was huge mistake.

Have issues it would stumble sudden REV then bang in 3 gears so hard that I was afraid I blew up transmission. That was 95 F250 with 351W

ok ok....i was a late eighty's baby. i am so interested in this since i have no codes, tune up is new with new auto lite copper plugs, taylor wires, accell cap and rotor, msd coil, and all my maintenance is up to date.... like mattri was saying, it starts to stumble only at a certain point. if you give it gas, then it smoothes out. if you let off, it smoothes out. i do have my timing curved to 12 deg., but this stumble was present prior to that when it was at the factory 10 deg.

There could be problem that you didn't use motorcraft for that. They are really strict what parts we use. Aftermarket parts for ignition system won't work it would short out and cause tons trouble.

Autolite plugs cap and rotor. Replaced them all about 6 mo ago. Truck just started doing this about a week ago.

still no answers, mine is doing the same thing. it doesnt matter what gear i am in but it will do it ussually at 1/4 throttle

I personally don't have a 6 cylinder. But I know that the 5.0 in these trucks were bad about crossfire between cylinders 7 and 8. I had this problem on mine. the cure was to make sure that those 2 spark plug wires were not run parallel to each other. I just crossed them at 90 degrees where i had to and zip tied them to keep them apart. It might be worth asking some good 6 cylinder guys about this.

well i pulled off the vacuum hose that goes to the egr and that solved my problem, now i will be making me a plate like what some other guys have talked about.

Interesting....

I'll have to look into mine. Starts perfect, runs perfect but when you wanna rev while in parked, it kinda misses, like it runs outta gas, let go the gas then floor it again, and revs right up fine.

I have no idea what rotor, plugs, and wires that's on it, I just bought the truck 1 week ago.

Still getting use to the whole EFI thing, I never had any EFI vehicles before.

That's about what mine does. Runs good otherwise, it's strange.

mine kinda does the same thing...when the trucks cold and I rev it I can see the RPM gauge dip down and sometimes stalls. When I changed the O2 sensor and I started it without it in it would rev up fine...cold or hot. and I could never figure it out

what are you gettin with 2 degrees of difference in timing?