I have a 91 SI hatch thats pretty stock. Someone before me swapped out the D16 bottom end with a D15, but it retains the stock head and intake. First off the speedo doesn't work. Secondly at idle sometimes it just dies. It will fire right back up but if it sits long enough at idle it will die. I feel it stumble some when driving about 30-40 mph. Not too noticeable but I'm tired of it doing this. No cel on start up but after driving about 15 minutes it comes on. Any ideas? I have replaced plugs, wires, ign mod., coil. Also, complete fuel system has been replaced. I'm kinda at a loss as seein it doesn't do it all the time.