hello guys,i have a missing on my fuel injected 13b when i go over 3,000 rpm and when i let go the gas the rpm keep on going up and down wht could it be?

 

A missing? A missing what? Or are you talking about a miss, like a missfire?
About those RPM's going up and down, does it happen only after you accelerate or does it happen everytime the engine is idling?
And what car is it? A FB or a FC?

 

its a misfire when it idles sometimes it does it and sometimes it dont but lately it been doing it when i drive it it sounds bad i change spark plugs,cables,ignition coil and all the electric thins and it still do it is a 1984 gslse wht could it be

 

Sounds like you have a vacuum leak, a maladjusted TPS, and dirty injectors.

 

thanks guys for your help ill get that checked out