Taking a close look at your photo, I might be able to provide some input on the dartyness of your steering.
The ball joint at the pitman arm end of your drag link appears to be an inch or so lower than the frame end of your track bar. When you're cornering, the chassis tends to roll around the axis of the frame end of the track bar. Now, any mismatch in the location of the pitman arm end of the drag link vs the frame end of the track bar results in an additional lever arm that ends up either amplifying (drag link end below the roll axis) or dulling (drag link end above the roll axis) the steering feel.
Now, imagine you're going into a left turn. The pitman arm pulls the drag link to the left and the body starts to roll to the right. Because of this body roll, the pitman pulls the drag link even more to the left and amplifies the turn input. The same thing happens when turning to the right because now the body is rolling to the left and pushing the drag link to the right.
Here's a little test - disconnect your sway bar. Does it get worse (the dartyness)?
Now, I'll give the vagueness a shot: When your drag link is at a steep angle compared to the tie rod, the initial steering inputs you give end up simply rotating the tie rod. It will rotate forward when you're turning right and backward when you're turning left. This effect will be diminished to the point of going away completely as the angle between your drag link and your pitman arm approaches zero. So, this is why your steering became more vague than what you're used to when you installed the 2.5" lift. This effect is called "dead center".
So, how does one fix all this? I would suggest a tie rod over kit to decrease the angle between the drag link and the tie rod. But, you need to make sure that your track bar receives a similar change in angle so that it ends up parallel to the drag link. To further complicate things, you need to make sure that the frame end of the track bar ends up approximately level with the ball joint of the pitman arm end of the drag link. Slightly below is ok but slightly above is still no good and prone to dart with steering input.
I know this indicates a drop bracket for the frame end of the track bar and, like was mentioned earlier, this is not as strong. I will definitely vouch for this as I had a drop bracket once and it broke on me at 65 mph on the freeway! But, this is necessary to get the proper steering geometry.
One final item of note - simply glancing at the relative angles of the track bar and the drag link can be misleading. You need to imagine a line drawn between the centers of the ball joints of the drag link and compare this line to the angle of the track bar. Usually this reveals a difference in angle between the two links that would explain any bump steer.
Sorry about the long post...but steering is definitely not simple and the relationship between the drag link and the roll axis is rarely explained.