2003 5.7L 1500 Ram with 79K. 2 days ago while driving on the highway at 60 mph my truck felt like it was missing on 1 cylinder- unmistakeable vibration, abnormal exhaust tone (that loud BLAAAAHHH sound), and very sluggish when i put the hammer down. When I am on the regular city streets, everything is fine- smooth idle, normal acceleration, normal exhaust tone (I have a Flowmaster), basically it is fine. The problem is only noticed at highway speed. There are no malfunction lights on on the dash, all gauges read normal. No codes stored in the computer. Plugs have about 30K on them, fuel pump sounds good when truck is keyed "on", & it starts fine. Nothing has been done recently to the truck except routine maintenance. Any thoughts?

 

Another note- today I was driving in the city and put it in "2nd" and it drove smooth all the way through 4500 RPM. Put it back in Drive and and it started acting weird again. Hit the O/D off button and it still acted weird. Transmission related????

 

My 03 2500 4x4 5.7 did the exact same thing on saturday night. It seems fine now? But I would like to know what is goin on?

 

I just took it to the shop today. I have a broken leg so doing any trouble shooting on my own is out of the question. Mine seems a little intermitent as well- like if it's warmed up (or warm outside?) it doesn't do it, but it definately does it in the morning when I am going to work- cold engine, cold/cool outside and I told the shop this also. I will let you know when it gets diagnosed and fixed.

 

Okay got it back from the shop...the culprit? Bad U-Joints. I've had u-joints go bad in vehicles before, but this one seemed different. I didn't get that "clunk" when going in and out of gear with the truck which would have automatically made me suspect u-joints. Glad that is all it was tho!!