[65comet]

My first thought for this vehicle was main cat clogged with the insides puked out by the first two pre-cats. Though you replaced them, I would still disconnect the main cat at the front and see if that changes the way it drives by relieving back pressure.
Second thought is the radiator has cracked internally and is leaking anti-freeze into the tranny fluid cooler. This is hard to catch and leads to a destroyed trans, but also causes these types of symptoms.
Third thought when I saw the battery light comment is that the alternator is going out, probably an internal diode, with it opening a connection when it gets hot. This leads to low voltage and the computer not working correctly.