Shuttering @ 45-50mph

[slepe67]

Truck has 183,000 miles & it's bone stock.

I jsut added new fuel lines, filter, FPR Shim, no fuel pressure guage. I've been meaing to add it since I shimmed it, but havent had time.

After all this work, I get on the Parkway to go to work and the first time it did it, I thought the shuttering was the bumpy road. Then it kept doing it until I added or removed throttle.

It now does it at 45-50 mph constantly. It SOUNDS like it is running fine, and doesnt seem to have any sort of loss in power; even when I get on it.

I dont remember if my truck shuttered before I shimmed it.

Sounds like fuel delivery, right? Fuel pump?

Thanks in advance for any suggestions or input! Cheers!

[rolsmojave3]

Have you run it enough to get any air out of the system?

[slepe67]

Yeah, I've put over 4,000 miles on it since the tune-up.

It does it around 45-50 mph, 1200 RPM.

I was thinking tires, but wouldnt the vibe change with speed? This changes with variations of the throttle.

[E55 Bulldog]

Check the balance of your tires, that 40-60mph zone us the key shake zone fir and off balance. You might not feel it as much when the engine is being throttles since these engine vibrate a lot too

[slepe67]

Just put new tires and shocks on it. WOW! What a difference.

The old tires didn't LOOK bad, but they must have had a blown cord or two. That thing got violent yesterday on the way to the shop.

Thanks for the help gents!