My 01 tundra can bog down under load - going up a long hill or towing a trailer - with the speed and RPMs steadily dropping until it finally downshifts, and the RPMS shoot up to 4k or so, but I don’t regain much speed. This is without cruise control. If I have the cruise control on the problem does not occur. The truck slows, but in a normal way expected under the circumstances.
The CEL is not on. No codes are being recorded. The Tranny fluid is full and smells fine. Ideas?