2004 Ford Escape - replaced both lower control arms and new ball joints. Then went and had a alignment. When accelerating or going up a incline at 65-70 mph car begins to shutter and knock in the front end. It was also was tuned up recently. It doesn't do it going down hill or on level road. What is the problem?

 

I'm sorry but my first thought was this:





Seriously, what you describe is hard to diagnose on the Internet, especially since you changed so many things that could be responsible for those kind of symptoms.

Offhand, my mind thinks of:

- Tires - out of balance, not installed correctly, separating tread, whatever

- Incorrectly installed or wrong front end parts

- Wheel alignment not done correctly

- Engine/drivetrain having problems under load

If the engine had been tuned up "recently" but had been driven and these problems weren't there then, chances are it's not an engine-running problem. If the problem (symptoms) began directly after all the front end work, then investigating said work is in order.

 

I could be an engine misfire which only occurs under heavy load. See if you can cause the problem at low speed.

 

Try turning off the overdrive when it's bucking.
My '01 had a similar issue when one of the COP's was starting to fail. Increasing the RPM stopped the bucking so I knew it was not a mechanical issue with the suspension.

Dropping a single cylinder at speed in overdrive creates a resonance that is amplified through the driveline and makes it seem like the vehicle is falling apart.