toyota tacoma 2007 vibration

i have a 2007 tacoma 4x4 automatic and for the past 6 month i have a slight shudder at every up shift and also when coasting from about 1200 rpm to a dead stop; the dealer changed the front driveshaft and then the complete rear driveshaft and joints and main support to no avail then a top mecanic flew in from toronto and after checking for the problem told me that the problem was known to toyota and that they were working on it since then not a word from them and every time i talk to dealer i do not get no answer i beginning to think that the dealer is pulling my leg hoping that i will forget it has anybody have the same problem thanks