I have an 01 Bullitt that I recently replaced the battery terminals on (about a month ago). After doing that, and driving roughly 800 miles in a mix of rural/city/and freeway, I took it in to have it smogged and the 02, 02 heater, and cat sensors weren't ready to test. My shop told me to take it back and drive it some more so I put 200 more miles on it and came back with the same issue. They told me to disconnect the battery to reset evrything, then do the drive cycle. I did that, plus put 300 more miles of mixed use driving on it (mostly freeway, but my daily commute is a 100 mile mix of rural, freeway, and city driving), and they're still not ready (and now a fourth sensor is showing not ready, though they didn't say which).
I left it with the shop to diagnose, and they did the drive cycle as well other diagnostics, but they have no idea. They had me pick it back up and advised me to post this question on forums and ask for help. I googled this question like crazy, but it seems to mostly pop up on later Mustangs, not so much our 4.6s.
The car is bone stock except for a K&N air filter wgich has been on for over a decade. Has anybody experienced this? The car also overheats a bit in really hot weather if I'm stopped in traffic with the AC on (I'm not sure if that's related, but I thought I'd throw it out there). Any help/advice would be much appreciated!