I'm quite used to seeing the torque converter stall RPM on my truck under the following circumstances: High altitude: elevations over 9000 feet where the engine can make only about 50% (or less) of its sea level power. Load: 500lbs of people/cargo in the truck and a 3700 lb trailer in tow. Grade: 15% to 20% (or higher) such as a campground exit or secondary mountain road.
What happens: I floor the throttle, the engine RPMs rise to about 2200 and stabilize (TC stall) and then the truck slowly, but ever so slowly begins to move. Under the above conditions it typically requires around 10 to 20 seconds just to get up to 20 mph (time depends on the exact altitude, air temp/density, and road grade). Engine RPM begins to rise above stall RPM when the truck finally gets up to around 10 mph. My truck is the Tundra V8 BTW.
I might add that acceleration in general is glacially slow even on a level road when towing at high altitude...at WOT a zero to 60 acceleration requires around one to two
minutes...and nearly a mile of road. At the end of a typical Interstate on-ramp I've often only managed to attain 45 to 50 mph so merging can be rather interesting in even moderate 75 mph traffic.
