I apologize for this novel but I have a long question. I have an 04 4x4 with the 5.4, and have about 94k miles. A while back whenever I would put a little foot on the throttle and the rpm's started to go up (over 2k rpms) the entire truck shook suddenly and the gear shift was very harsh, and it did it all the time. I took it to the dealership and they didnt know for sure what it was but flushed the transmission and the problem went away. Just yesterday, however, the truck started a random bumping and would jump forward several times like it was trying to shift gears but couldn't whenever i had steady low throttle on below 2k rpm, especially going uphill. I dont know what the problem is and obviously neither does my local Ford dealership, any ideas what it could be? I'm not even sure if its transmission or something else, it just seems like it. Any help would be appreciated. Thanks!

 

Have you replaced your plugs?

 

Mine seem to do that when I would be in the 40mph range, it seemed to be right at the trans shift point. I started running 93octane and havent noticed it but I just had to take my trans out and put a new front pump seal on it. Runs Great!! I'm sure my plugs are part of that. im @ 105k.. As mentioned plugs.. and try switching gas if you aren't already running premium

 

no i don't think the plugs have been replaced. and as far as the gas thing, that could work but i'd rather not have to pay for premium at the pump, i struggle to pay for regular fuel already lol

 

I had the same problem and I resolved the problem by changing plugs. When changing plugs I found that two plugs had broken porcelain and electrodes, the coils held them together but caused a miss fire that showed up in the 40 mph range especially when going up hill.

 

You are also reaching the mileage that you should have your timing chain guides and tension rods replaced. (A good $800-$1000 job at dealer) I say this because after doing my plugs I had to do the guides and tensioner rods to get the power back. The miss firing plugs caused the electronic timing control changed the timing so many times to compensate it wore out the guides and tensioner rods. Good luck.

 

Thanks for the help! I took it to the dealership just to let them check it out and they said the plugs needed replacing and i had least one bad coil. they replaced it and i am going to pick it back up soon. i'm hoping this $300 fix will solve the problem, sure will be alot easier hit to take than $800-$1000!

 

If your getting the plugs and bad coil done for $300 that is way way cheap. Average dealer plug job on these is $400-1000 depending on if the plugs come out clean.

 

Mystic, I think he meant they were recommending plugs. Thats probably for the diag, coil, and labor only.

 

Ended up being $401, and all they did was change the plugs and all the servicing involved, etc.. . It got the bumping out though and it rides smooth as ever now.