car hesitates when changing gears on 2003 Lexus GS430

no codes no lights, running premium gas, hesitates when changing gears, dealer says nothing is wrong, i just bought car and thats what previous owner said.

Asked by for the 2003 Lexus GS430
Throttle postion sensor my dealer could not find it either
I've had the same problem with my 2004 gs 430 since I bought it in 2006 my dealer says nothing is wrong and they didn't notice the hesitation. Now my gps screen is glitching, changing different colors and sometimes not working at all. I'm wondering if anyone else has had this problem