Thanks for additional information... Let's see if I can provide further symptoms/characteristics of the problem.
When the fault occurs the car never makes it into 3rd. When it's acted up at highway speed there's a loss of power and then the car will no longer make it out of second gear. To answer your last question, when the fault occurs the car definitely chokes and sputters - almost sounds like it wants to backfire. The tach will swing rapidly between idle and 2000-2500 RPM, with an associated learching of the car (that's with the accelerator floored). However, you can just lightly press the accelerator and the car will move along fine at a slow rate of speed (as long as RPM do not get close to the shift point). But the minute you hit that point, the tach will kick right back down to idle (with an associated deacceleration of the car). It does not feel at all as if something is holding the car back (like the brakes being depressed).
It feels like taking a car with a manual tranny up in the RPM range in 1st and then taking your foot completely off the gas. Now, imagine rapeatedly pressing and removing your foot from the accelerator each time you get the the shift point with a manual transmission, and you have the feeling of what this car does when it has the fault.
Are these characteristics consistent with the L5 sensor? It did not immediately feel like a typical engine timing problem... when the fault is occurring the motor runs fine until it hits that magical RPM point.
I checked the kickdown switch... no problem there. It does not stick when depressed, and there is no carpet interference.
Do you want me to check the torque load while the car is running normally, or the next time the fault occurs? Normally will be easy - but who knows when it will die again (although my wife is travelling this week, so there's a good chance
Again, thanks for the help... I've been trying to isolate the cause of this problem for quite some time now. You've done more in a couple of replies to help me than all the other efforts to date combined.