Anything is possible. I doubt the cat is a problem. You can check it with the economy gauge on the dash. When you are experiencing the problem hold the accel down and hold the engine at 2500 or so. Once a steady RPM is established, look at the econ gauge. It should be steady and well out of the red.

I don't think you have an idle circuit, because you said the problem occured at cruise speed.

After you've down the checks I suggested, I would next suspect a problem with intermittent fuel dlivery. One of the two pumps may be crapping out. The fuel pump relay may or the OVP may be failing.

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