i got a 1990 240sx and when i start my car i have to rev it for about 10 secs then if i let off the pedal it idles rough for a minute or 2 it has a custom intake...custom made by last owner...any thoughts on what it could be?

 

tune up

 

ya thats what i figured i forgot to say its been sittin for a year so its definately in need of a tune up thanks