So my dads mechanic said my transmision was failing so I bought a used transmission that has a 6 month warranty on it . Had it installed and it still has the same problem. Now I question whether the problem is the transmission. When shifting to next gear, the car shakes for a few seconds. As you continue to go it kinda shakes again, unless you let go of the gas pedal for a bit then it goes to the next shift. it wont go passed 35. The D , for drive, is blinking. What could the problem is