Throttle body 'T" how many holes?
 

I was taking my '98 Boxster (5spd) throttle body apart and cleaning the idle control valve today to try to 'cure' a sometimes erratic hunting idle and noticed the rubber sleeves holding the T plenum connector had a small port on each side. the right was connected to a small tube, but the left had no such tube. What do you do with the small hole of the left rubber sleeve? Is this the right part for the left side or did previous owner used 2 rights ? Do I plug it ? Does it matter ? http://986forum.com/forums/uploads01...1413916657.jpg
http://986forum.com/forums/uploads01...1413916807.jpg
Visible part # is PXO 416 410-1

Right side is SAI and should lead to a check valve. No idea about left side. Can't just be open. That may be your very issue!

Sorry what does SAI stand for ?

Secondary Air Injection. Start up feature that adds air with a small pump and reduces emissions.

It should go to a rubber Tee. One end of the tee goes back to the vacuum canister and switch under the manifold tubes between cylinders 1 and 2. The other end goes to a switch between the manifold tubes at cylinder 4 and 5. This one also branches over to the air damper butterfly on the front cross over tube.

Here is a photo from when I was rebuilding. I took this for someone else who had a similar problem. Note the White and Black check valve then tee.

http://i1199.photobucket.com/albums/...psc230feeb.jpg