Hi,
I'm having a problem with my '96 Ford Escort LX (1.6 Zetec, ~100k miles)...
The car always starts fine with no problems, however, after about 10min of driving it will begin to judder/jerk as though it were misfiring. It is possible to ride through this but it can last up to about 15min during which time hard acceleration is not easy or even possible. Once the problem has cleared the car will be fine for the rest of the journey, no matter how long it runs for. If i pull over when it begins to occur, i can see the engine tries to idle at its normal idle speed (~800-900 rpm) but then seems to loose revs and drops suddenly which sometimes leads to stalling.
I've changed the spark plugs and HT leads, even the oil to make sure its the 5w-30 (but not a ford brand though) and i'm beginning to think it could be a problem with the Engine management system. I would dearly welcome any ideas as to how to resolve this! (particularly as i'm reluctant to hand it over to a garage who may waste plenty of hours as the fault only becomes apparent after 10-15min of driving and therefore be difficult to simulate in a garage.) Many thanks, Damian