Did you use new gaskets on the throttle body? You might have created and intake leak. Some intake leaks (gasket related) leak cold. Heat applied to some thing make is expand. Letting something cool off contracts and object.

What plugs are you using. I have a hard time re using flooded out plugs in less i clean them with this http://www.jcwhitney.com/webapp/wcs/...atalogId=10101 Mini sand blaster.

http://www.spark-plugs.co.uk/pages/t.../diagnosis.htm 2nd one down is covered in carbon. Carbon is a better conductor of electricity then air so the spark never jumps the gap.