tokleman yanass

when my '86 300e has been sitting for a couple of days it starts fine, runs for 8-10 mins perfectly then starts missing and sometimes cuts out, I can keep it going by left footing the brake and keeping the engine revs up. If I let it cut out it wont start for 15 mins or so and then it usually starts up and clears up. The system is ke jet. My best guess at the moment is the temp sensor which should be sending some messages to the ecu about that time to start tailing off the warm up mix. It's such a specific, consistent problem it ought to point to one part of the system but i'm a bit mystified. I'd appreciate anyone's ideas...also, does anyone know any sites where I can get more detailed tech data on the ke jet system, I'm not having much luck finding good stuff.