I have an 04 navigator that seems to "jerk" or miss fire when I am accelerating on the highway. It has 60,000 miles on it and I am scared something is really wrong with it. I want some advice before I take it to the dealership. My dad seems to think that it might be bad gas or a bad fuel filter....any suggestions??

 

Is the service engine soon light on?
I had a similar problem with my '00. Driving around town, I did not notice anything. When i got on the highway, I had a terrible shake, couldn't get up to speed. By the time I got home, I did get an SES and when i pulled the code I had a misfire. Took it to my mechanic, my right catalytic converter was completely clogged and my left was nearly clogged, 2 psi on the right and 15 psi on the left.
I had both of my cats changed out, all eight plugs and COPS, fuel filter, upstream hose for the DPFE sensor.

Total 1300 bucks.

I bought my cats online and had them shipped to my mechanic, 480 bucks for both.

I bought my cops online, all eight, for about 90 bucks, delivered to my house.

Labor was about 700 bucks.

Get you car to the mechanic, hopefully its just a simple misfire and you won't run into the problem I had.

I bought the car, its a great car and I trust my mech completely. The car came with a internal drive train warranty and he ran through the whole thing and he says it runs like a top now.

Good luck and let us know what you find out.

 

I had the same thing on my Expy. Going 60 mph, I'd accelerate (like a half a pedal of gas) and would get a shudder. Never happened any other time except at higher speeds. I thought it was spark related since mine had 108,000 on original plugs. Started to change the plugs and the entire passenger side plugs were fine. In fact the plugs looked perfect with no white or grayness on the diodes. Started on the driver's side thinking, I'd find my problem. As it turned out, on my 97 I had to remove the fuel rail (some do, some don't) to remove the last 2 plugs on the driver's side. I'm glad I did, because when I pulled the rail off, my front injector came out with it. I didn't think any thing of it until I wiped the gunk off the injector. The nipple/tip of the injector had a hair line crack in it. At that point I figured I better inspect all of them. Turns out injectors 5, 6, 7 all had similar cracks. The rest were fine (no cracks, etc). I decided to replace all the injectors since I had to get three. Well new injectors are about a $100 a pop for FOMOCO and I said forget it. Got on Ebay and found a vendor that has entire sets of refurbished injectors. Got a set for $150 shipped. My vehicle runs like a champ now. Next thing in line are new COPs as soon as one goes out, I'm doing all since the job is labor intensive and I hate tearing into it.