I have a weird vibration on the highway when I let go of the Gas Pedal at 70MPH+. So basically if I cruise at 70MPH and then let go of the Gas to slow down I will feel a shake/vibration in the car from the front end for about a second. This does not happen however under 60MPH. The car use to never be like this. I don't think any of my mods would cause this.
Mods:
HKS Intake
Tein S Tech Springs.

This is had never happened before. Thanks for any input. I have 23,000 miles too.

 

front end vibrations are usually related to poor wheel balance and/or alignment.
Start there, and g/l

C.

 

Yep alignment, and tire feathering.

Some '04's have a need for compression rods-- ask your dealer today!

 

Oh I see. I let my springs settle in and haven't got the alignment. I will give this a try this week.

 

We tried everything for the vibration... The dealer finally gave me new wheels and tires.. PROBLEM FIXED. It was the wheels...............

Howerver about 10,000 miles on the new wheels, the vibration came back, and I still have them at 73,000 miles. now dealer won't even look at it anymore.

 

I have aftermarket Wheels.
I actually found my answer though. Poor Wheel Balance. Alignment was ok but the wheel balance was way off. WAY WAY Off. The company I bought them for didn't care and just mounted them basically.