Syracuse

I have problem with my car Lexus RX300 2003 and hope to find answers on thes forum. Lexus RX300 1999-2003 Diagnostic in Advance Auto Parts show P0021 Camshaft Position Timing Sensor need to me replaced. Also: Misfire P0300, P0304 CYLINDER 4, 5 AND 6 Symptoms: While driving in about 60 mph feels like transmission does not switch correctly it idle a little then shift like a punch. Never happens before. If idling on tachometer show less then 1000 rpm and not stable car shaking, rpm move up and down. Tried solutions: Replaced Spark plugs; Replaced Coils on 4, 5, 6 Replaced Camshaft Position Timing Sensor (bought from Pep Boys) Nothing change! Same symptoms! I even removed sensor and start a car for minute and nothing changed. Guess maybe Pep Boys sold me defective sensor or my problem not relay to all what I did. lexus rx 300, camshafts, misfires, p0021, p0304, Will appreciate help. thank you