U seem to have tried everything that you should have done and even things that you should not have done, I'm assuming u have checked your tire air pressure etc, the only thing left is remove your front tires and have them balanced, when they're spinning on the balancing machine check for abnormal bumps and jumps, this will signal if the rims are bent or misshaped or if the tire has a swollen side wall or something , I would also suggest you stop going to the mechanics who had u change the tawa and have them re-tooled, re-tooling is not a smart decision, do the wheels make a whirring sound like the bearings are worn or something although this shouldnt happen in a 2008 vehicle, did u buy the vehicle new or did u purchase it recently as a used vehicle?