Hello guys, I have a weird problem. My truck is an '04 5.4L automatic. Lately my truck has been jerking, almost like the transmission is slipping maybe, but only when going above 40mph and staying under 2krpm. Hasn't had a problem shifting gears. Also getting to where it does it rarely at like 70mph. I have tried putting some lucas transmission into it and didn't help at all. Any ideas??

 

Not sure if thread title was intentional....
.
How many miles on the truck?
Are you getting a CEL, flashing or steady?
Spark Plugs/COP boots and springs ever been changed? Sounds like you may be getting a mild misfire.
How about that transmission fluid? Condition? Proper level? Changed recently?

 

Lucas transmission additive makes me cringe...

You're likely experiencing a low grade misfire. Like mentioned above, your service history can help us better help you.

 

new Boots and plugs . Clean all cop connections on coils and to them . Contact cleaner and elbow grease ---Corrosion . Oem coils rarely fail .
But since you are thinking of your transmission change pan to drain type ,change filter then change fluid 4-5 quarts at a time every couple of weeks .

 

Probably coil or plug. Clean throttle body, replace fuel filter, air filter ?

 

Yeah now that I see it the title isn't the best... The truck has 162k miles on her. The boots have never been changed. The past service is regular PM's on it. At 95k had the trans fluid changed, spark plugs changed, and whatever else Ford did at the 95k mark. Transmission fluid level is fine, condition should be good. Has 62k miles since changed. Fuel filter was replaced a couple years ago with the throttle body being cleaned. Couldn't hurt to do it again. But I was thinking it needed a tune up or like you said new coils and plugs. Once it did a fast shaking when I went to pass someone and the engine light blinked for a minute.

 

A blinking CEL is a classic sign of a mis-fire condition.. suggest you change plugs with motor craft SP515 and get new boots and springs.. COP's can be cleaned and tested or replaced .. up to you.

 

Change plugs and boots. Do it sooner than later, when mine did the exact same thing, it ate the passenger side cat as well...

 

can you buy just the boot part?? All of them on amazon come with a coil it looks like

 

Changing the plugs (originals with 111,000) solved that problem for me. I was certain it was a transmission as I had an issue with y 99 F-150 transmission and replaced it. I took it to Speedy Transmission shop and the guy told me it was not the transmission but likely the plugs. (no charge -- he definitely will get my future business!) From there I cleaned the MAF and Throttle Body and added SeaFoam into the gas tank. The problem persisted so I tackeld the plugs. I am currenlty am down to one more plug to change when I get a spare moment. with 7 of 8 changed the issue immediately improved. When I started hearing about the Catalytic converter damage with an ongoing misfire issue I knew it was time to jump on the plugs. Also throughout this no codes were thrown.