need help

i know its probly covered somewhere here and ive been looking but can find much info...

just got an 86 crx carburated and its giving me hell.
it ran good when i picked it up but it reved at almost 3 grand, but it would run. now everytime i start it it dies. it needs constant gas to stay running. but then out of nowhere it will run and stay at 3 grand again! i gave it a tune up and what not...going to atempt carb ajustments but dont know where to start. some vacuum lines look new p/o may have mixed some up maybe? any help?

thanks