my 89 240 will start and run for maybe 10 minutes, then the check engine light will flash and the engine will stumble at the same time. finnally the engine will die and be hard to start and no power. the codes are 1-2-1 (bad signal from amm) and 3-3-2 (no burn off of hot wire). i replaced amm but symptoms continue. thanks

/// Have you ever noticed anything else fail when the engine stops? Ever lost radio settings? Start with the basics, the battery cables, the power path to the engine electronic controls. If there is an interruption of power you may get codes that have nothing to do with the cause of the failure.

Over the last several months there have been posts of hard to find troubles that worked out to be bad connectors in the power path to the engine controls.

Use jumper cables to bypass the negative battery cable and run voltage drop tests on the positive battery and starter cable. Proceed to any connector in the power path as well as all ground points for the engine controls.

Pull the part number for your ECU and see if there is an entry for it in the archive. Sorry I don't remember more for you. Repost if you do not get better information.