I have a 2004 XLT supercrew 4x4 with about 150,000 miles with the 5.4 motor.I noticed that when entering an interstate at around 50-55 mph it feels like the tranny slips. There is a jerk,jerk,jerk than it stops,it doesn't do it at any other speeds and only getting on interstates. Runs fine in town.No lights on the dash or codes,fluid level is normal and clean.Took it to the shop but they could not get it to do what I described and suggested a specialist.I did have a caliper sticking but it was replaced and it's still doing the jerk,jerk,jerk. Could it be U joints? Any thoughts would be appreciated thanks.

 

It's probably one or more ignition coils or spark plugs causing a low grade misfire.

 

i have the exact same truck (04 lariat screw 4x4 5.4 with 158K) and same thing started happening to mine a couple weeks ago. i thought it might be the transmission spark plugs or coil packs also, i took it in and he said that it was the Common Rail Valve, im taking it in next week to get it fixed.
mine didnt throw an engine light untill i drove around with it happening for about 2-3 weeks, now my engine light is always on and it gave a p2006 code, intake manifold stuck closed.

 

???????????? The spark plugs and coil packs are in the engine, not the transmission.

 

ha yeah i know that...i forgot the comma after transmission... i meant at first i thought it might be the transmission...or the coil packs...or the spark plugs.

 

I had something similar happening when putting it to the floor. However I could easily tell it was the engine *******, causing the jerk,jerk,jerk. Replaced spark plugs, now all is good. However I could easily tell it was the engine. And when my tranny slipped on my 04 it was one jerk, not multiple. And I knew it was the tranny. All good now. Hopefully my input helped or opened up possibilites, good luck.

 

Thank you all for the input.Very helpful! I will check all those things until it's fixed. Funny it only happens on interchanges where I have to brake going into them and when they are curved then on acceleration is when it happens but not on straight interchanges.