Long time reader first time poster.
1995 F-150 4x4 I6 Auto Tranny

Engine stumbles and jerks at idle, and when you hold down the accelerator about half way it'll also miss out a little while parked. When driving down the road it will do the same thing when you're in that same spot in acceleration, or when coasting down hills.

Per previous threads on hesititation I've replaced:
Plugs/wires/cap/rotor/distributor(damn cap bolts spun off on me)
Throttle position sensor
New fuel filter
Sea Foam in Gas tank
Truck doesn't throw any codes

If you have any other ideas to help I would love to hear them.
My last resort is taking it to the dealer.
Thanks and Thanks for all the other posts they help!
I6's rule!

 

This may or may not be what's wrong with your truck, but my '85 has a bad hesitation at a certain spot in the throttle due to a leaky intake manifold. A couple of spots on it just will NOT seal up, no matter what I do. I'll be replacing it in the next couple of months with an aftermarket one.

On the I-6, I would check all the mating surfaces where the intake meets the head. An old '64 Chevy I had a LOOOONG time ago had a 250 I-6, and had a horrible time with manifold gaskets leaking on it. The fastest way I know of to check this (and it probably isn't the best, but it works) is to start it up cold, let it idle, and spray starting fluid (ether) lightly around all the spots on the intake. If it's idle speeds up at a certain spot -or spots- you've probably found your leak.

 

I'll try that when I try among other things cleaning the IAC and EGR. I also need to do a vacum check and set the timing. Although it says the truck sets its own so I have to read up on that as well. Thanks for your help.

 

you set the base timing at 10 degrees btdc with the spout out.

 

I would check the timing, check the vacuum, and also test the fuel pressure.

 

Excuse my ignorance but what spout?

 

The spout is a plug in the wiring to the distributor that disables the computer controlled spark advance. It's a small gray plug that you must remove in order to set or check the timing.

 

Well I finally got my craftsman timing light and checked the timing.
It'll only get close to the marks on the #2 plug wire so I think the wires on the dist are off by one. I'm assuming because the truck runs fine other than the stumble it has.
I'm going to replace the CTS next and see what that does.
I've had the distributor in and out so much I could do it blind folded.

 

ceck for an intake leak had to replace head took 4 mechanics to figue it out bad seal on intake manifold.

 

I had some of the same symptons, turned out to be a cracked intake manifold and very dirty injectors. I took the injectors to a diesel injection specialist that had the equipment to clean gas injectors. Cost $180 to clean and rebuild all eight injectors and picked up the manifold at a salvalge yard. Runs like a champ now.