Have you Ohm'ed out your fuel injectors? Just a random thought, perhaps one of them is intermittently failing. If you have a shop locally that can clean/rebuild/flow balance them, it's totally worth the peace of mind and potential mpg gain, not to mention if a bad injector is the source of your severe hesitation that would fix it.
I know that when I extended my O2 sensor in my VX to its new home, I had forgotten to swap out the new calibration resistor that was matched to the new L1H1...that was some severe hesitation for a few miles until I pulled over and swapped it to the correct resistor.
I mention this because I would like to know what value your calibration resistors are in your L1H1s. Would you be able to use some needle nose pliers to pull out the white insert on the sensor connector and look at the numbers on the flat side of the calibration resistor? Or just use an Ohm meter and measure the resistance of pins 3 and 4 and post here if you don't want to pop out the resistor from the connector.
Here's a little topic about the resistor.