[instantkevin]

if you had smoke coming out of the exhaust, that means there is a liquid/substance being burnt in the combustion chamber that should not be in there. this is probably antifreeze. Sounds like a leaking head gasket to me. you need to do a compression check.

what compelled them to change all of the fuel system equipment? what did they find that made them think that was the problem?

was the smoke only comin out of the cat or was it coming out of the muffler too?