97 Buick lasabre

[BrokewithcarproblemsHELP]

Car runs great out of nowhere it’s doesnt want to switch to 2nd gear the rpms rev but not gaining much speed eventually with coasting it’ll let me pick up speed this gets worse after it gets heats up???? Speed sensor?

[carriedi]

doubt it would be the speed sensor but stranger things have happened. scanning the transmission could give you the information on what to look at the slipping problem.

Fluid level is good, right?