I've read over the last 30 minutes like 10 or so questions. But I haven't seen on quite the same as my problem. Though I have a feeling I know the answer already.

S5 '90 GXL N/A

4k miles on new street ported engine
No smog pump
Race Beat Header
Race Beat Down pipe w/ slience
Race Beat Cats

Durning my engine rebuild I didn't reinstall my 5/6th ports i just left them open and blocked off the outside connections, tubines, etc. I left the VDI still connected. Lately i've been getting poor idle condtions consisting of running around 500 rpms to the jumping idle (not sure of techinical term). Should I buy the block off plate for the VDI or should I hook back up the air pump? Atm i'm at loss on what to do.

Any input would be great. Thanks

 

bouncing idle is usually attributed to a vacuum leak