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The car was running fine, after a few short trips 30 miles or less over a few weeks it began to break up while driving. Sometimes it would take a bit for it to start up once turned off, but then id go for a loop (3-4 mile drive) and about half way it would begin to break up under load. It would idle fine, drive just fine up until that time then it would get worse and either shut off or not restart if i shut it down. I cleaned the carb, changed the plugs, installed a new fuel filter before the carburetor. I did notice a couple of the spark plugs had come out by hand using no force, one of which i was able to lift right out without turning....... what is the easiest way to repair the threads or get these plugs to stay in...... i believe this may be the cause of my breaking up issues. If anyone can assist it would be greatly appreciated. Thank you.

Definitely a source of concern. You need to torque the sparkplugs in properly to seat the metal gaskets and keep compression as high as possible. Anything less could cause blow-by and break down the ground between the plug and the head destroying the spark itself.
It sounds like there is no thread left in some of the plug holes when you comment that you were able to simply lift the plug from the hole.
You may be able to use a sparkplug helicoil kit in the affected holes, this will allow your plugs to thread in and be torqued properly to allow proper performance.
I have not dealt with this issue so I believe you may have to work with a supplier such as Max Merritt or Kanter to get advice as to what product is best for you.
Others may have had this occur and add to my comments before you decide the best course of action, but I feel you are correct in that you do have a serious problem that needs addressing before your car will perform properly.
Bob J.