Front End Problems on PT

I am having continued problems with the front end of my 2002 Chrysler PT Cruiser. Within the last 3weeks I have replaced:

1. Tires have been rotated, checked, and balanced.
2. New Engine mounts all the way around
3. New Front stablelizer links and tie rod ends
4. New Front Struts

After all of that here is the problem;

At low speeds, when I make a turn coming out of a parking lot I hear a knock that once I complete the turn is gone.
First thing in the morning on the highway on the way to work the car runs great for the first 30 minutes (can not notice much of a front end problem). After that I notice a terrible shimmy in my steering wheel as if my tires or tie rods are bad, it is really noticeable over 55 mph. The problem is that when I take it to be inspected, the shop can not find anything as almost everything has been replaced. Sometimes I also hear what sounds like some rubbing sound. Could this be a wheel bearing issue?

Is there anything on the car that has fluid or gas in it that once it is warmed up can exhibit the problems I am describing? Could there be something wrong with the steering column? The front end has given me so many problems over the past couple of weeks I am thinking about getting rid of the car but I can not afford it. Any suggestions?