my f-150 is studdering at 1500rpm. I have already changed the transmission fluid and replaced the coil in cylinder one. It only does it at speeds above 40mph. The truck has 89000 miles on it. Any advice would be greatly appreciated.

 

Does it do this when the car is i neutral at that rpm range, or only while driving?

 

It definitely does it while driving. I have not tried to do it in neutral. I'll get back to you on that.

 

I'll be waiting...[8D]

 

no it only does it while in drive and it seems like it does while shifting from 3rd to 4th gear????

 

I am assuming that it continues to do this from 40 mph on up, is that correct? Is it doing it only when you are on the gas, or does it do it all the time when you are in that speed range? Try pushing in the clutch (I assume you have a manual since you said you were shifting) and coasting in that speed range. If it only does it while on the gas, check your u-joints to see if they are going bad.

If it is only doing it in a certain speed range (for example 40mph to 50mph) then does it feel as if it is shaking in the front mostly, or the rear mostly? If so, check the wheels on the front or rear and see if the balancing weights are still on. Also, check to make sure one or more of the lug nuts have come loose.

 

actually it doesn't feel like that kind of stutter......it's more like it's missing or being starved of fuel. Someone told me it might be the torque converter, something about them faning it out wrong or something....