Alright, I've got 2 problems with my 06 SS/SC... I went to the dealer and they told me the car was fine... they were unable to reproduce the problem.

1-Sometimes, after heavy-driving, especially after hard braking in a down slope, I hear a "toc-toc-toc" in the rear wheels. When braking or using the handbrake, it stops. Release the brake and it comes back. It goes away after ~½mile. When I have passengers in the back, the problem is also there... probably because of the added weight, the brake will get hot faster. I've checked the bearing by lifting the car and looking for wheel play but everything is fine. Could it be the disc? When it gets hot, it curves and hit the side of the caliper? I know for a fact that my rear calipers need greasing, they are almost seized (handbrake not working 100%). Can it be the cause of the problem?

2-When the car is cold, lets say I start it, wait 10-12 sec for the rpm to go down then I go(during summer), the car has a tendency to bog down in 1st and second. The problem is worst if I shift the 2nd gear at very low rpm and then use more than 50% throttle. I thought it was throttle body problem (drive by wire problem) but I've check and when the engine floods or run too lean (I don't know which), playing with the throttle changes the boost gauge reading. The engine will do that on the first or second stop start. After 1 min, it's fine and the problem does not occur again till the engine gets cold. The only way I can avoid the problem is to rev the engine a bit to 2-3k during 0.5s (just a tap on the pedal) just before starting.. Then it's fine... It's really awkward.

The car has 44 000kms (~27 000 miles), I've changed the plugs and the air filter but it did not help.

The car is stock except for a K&N Drop In filter.

Problems History:
3 Months after my purchase, the dealer reprogrammed the ECU because car was running WAYYYY to rich... I was puffing black smoke everywhere! Then the dealer had to change the Down pipe (including the Cat) because I had a exhaust leak last year. It was probably caused by the fact that the car was running too rich and that clogged the cat. I changed the plugs because they were burned because the car was running too rich. They also had to replace the fuel pump because the car would bog down (almost as it does right now) at high RPMs, under high-boost situation when the fuel tank was < ¼ full.

Any Ideas?