I would suspect a plugged pickup screen in the fuel tank. If I'm right, you should find it runs best on the highway, and stalls when the screen must pass the most fuel volume, . . . which is during coasting. My '88 Grand Caravan did this on the two hottest days of summer, then I never had another problem until six months later. I can only guess the higher temperatures soften the plastic screen allowing it to collapse easier, but a tankful of cool fuel didn't make any difference with mine.
Now that I understand what was happening, you can also try disconnecting and plugging the vacuum hose to the fuel pressure regulator. This will result in an excessively rich fuel mixture during periods of high manifold vacuum, (coasting), and a lean mixture during acceleration, so expect it to run poorly, but it shouldn't stall.
If none of these tricks seems to affect the symptoms, try wiggling the ignition switch when it acts up. They are known for overheated contacts, and for burned connector terminals and a melted connector body. If this is the cause of the stalling, other things should stop working at the same time. Power windows, radio, and heater fan are usually affected.
Try switching the Automatic Shutdown (ASD) relay with one of the other relays. Although not real common, pitted contacts could cause overheating and a poor connection.
All three of these things can commonly cause a problem at regular intervals, like you mentioned. Nothing will affect when the ASD relay will act up, but problems with the ignition switch will act up sooner if you run the heater fan at a higher speed.
caradiodoc
May 21, 2009 at 1:47 AM
