have to close choke plate?? to keep car running-why??

Guitar Jones said
This is right on but I'd just pull the carb and take it apart. In my experience trying to spray it to clean the inside from the outside just doesn't work. It's running lean but you didn't do anything to cause a massive vacuum leak. Just pull the carb and clean all passages and orifices (don't you just love that word? lol) thoroughly.

It's the carb.
Closing the choke plate would almost instantly kill and engine that was getting anywhere near the right amount of fuel through the jets.
Plus the white stuff mentioned is probably a mixture of fuel, water, and who knows what.