Slayer, what your clutch sprung or unsprung? what you describe sounds like an unsprung clutch. You can get "pretty far" performance wise and not feel a difference in regular driving. An unsprung clutch is damn near impossible to drive in stop go traffic. And they usually show up around stage 3 like you had.
'Twas a sprung clutch.
2004 Aveo beater car
2005 Aveo LT. 5-speed beater car (DOA)