Howdy. Has anyone experienced this? I've provided codes also. And some test results when warmed up. Thanks!

1,000 miles ago my 2003 3.8L Montero Limited, auto trans, 220,000 miles, had been driven for 10 minutes in town and it started slowing down, eventually to 20mph. Playing with throttle did nothing, except keep it limping. No jerking or RPM slippage or revving. All gauges, RPM/transmission normal. Check engine light came on (but is always on for oxygen sensors). It was turned off and sat for 30 minutes. Started up fine and drove home 10 miles fine as if never happened. I was busy and forgot to check codes. Next day it was fine too. We forgot about it. 😆

I drove it for 1,000 miles, once through 4 mountain passes for 500 miles, no issues over that 2 day hard road trip. Then today, same thing occurs except on the Interstate. I could keep it to 40mph on level ground. It started slowing down from 80mph to 40 mph over a 3 mile distance. Manually moving gear selection did nothing. I limped it home 20 miles. I let it rest 45 minutes and started it up. Seems good again. As if nothing happened.

I pulled these codes and took these screen captures when it was fully warmed up again, but I hadn't touched the throttle at all. I just started it and let it idle to warm.

***The oxygen sensor codes have been there for 40,000 miles. Cleaning and replacing them did not solve issue, so I just chunked it to "old truck with dumb gadgets", as I don’t care about CEL (no emission testing) and everything else was good with it.

So there's 3 new codes which seem to be related to this random limp issue.
P0335
P2135
P0340

Anyone else have this happen and figure it out? Thanks!