I changed out a old motor in my 2002 sunfire with a 2003 used sunfire motor 2.2 OHV model due to the 02 motor overheating and the engine was full of water sludge looked like frosting everywhere. Anyway to get to the point. I dropped in the 03 motor. Runs great just the engine moves a lot and it jerks when i put it in drive. MOTOR MOUNTS??? and also the idles tends to go up and down i was told it was the IAC Idle Air Control valve. I have everything old of the 02 motor should i switch over throttle body's and hope for the best? The 03 throttle body is just full of sludge on the outside. and the 02 throttle body is full of oil on the inside due to blown head gasket and running it blown for over 2 months.