Have you considered the fuel distributor. In the SEs, it may be a common problem that beneath the fuel distributor you have worn rubber seals that permit fuel (gas and sometimes fuel) to be leaking out. You would notice an aroma of fuel entering your cabin. If so, your cars stalls. I would recommend getting your tech to remove the air filter and look closely at the fuel distributor for any signs of stress and leaks with all the rubber seals holding it in place.
126 tailed by a 203, 129 leading the pack.