Re: code:"catalyst system efficiency below threshold"
Sounds like it may be the cats too. I can't say for sure. One thought and it may or may not apply here but I've heard, at least on older cars, especially those built in the late 70's, early 80's can have cats that go bad, causing a restriction which can drastically affect performance, ie, make the car perform rather sluggish, if not very sluggish.
Looking back on it now, I wonder if I had that issue with an old '78 US Ford Fairmont I had. The cat would get warm enough that on warm - hot days, I can feel the heat waft up from underneath the car, making the car even more uncomfortable to be in on those days. Also the car had no A/C and poor ventilation except when moving fast. Also the car would take forever to get up to freeway speeds and no matter how I tried, it simply would not do a burn out. It was the 200ci inline 6 dating back to the mid 60's but with anti polution crap on it.
Just a thought. Since then, I've not experienced that issue in my last two Hondas and both had 181K+ miles on 'em when I sold them, the last one being yesterday.
I currently drive a 92 Ranger and so far, so good at 188K+ miles on it.