FT_TC3Racer
Try cleaning off your tires between runs. At my track (indoor carpet) the front tires pick-up a lot of sticky junk that can cake onto the tires. I use a little lighter fluid on a rag and scrub the tires (both front and rear) clean. Then I use traction compound as per instructions. When I do this, I get consistent grip through out the total 8 min run.
Keeping the tires clean allows you to better evaluate the car's setup because the car will be consistent and not require 1 - 2 minutes to come in.
Hope this helps